Amanda Bynes Troubling Behavior

Amanda Bynes just inexplicably railed on Rihanna on Twitter, saying Chris Brown beat her because she's ugly ... but RiRi got the last word and it was AWESOME.

Bynes tweeted -- and quickly deleted -- "@rihanna Chris Brown beat you because you're not pretty enough."

She followed that up with another insult -- about wanting to name her dog Rihanna. It's unclear what set her off.

RiRi clearly got wind of the deleted tweets, because she just posted the BEST COMEBACK EVER:

Don't mess with RiRi.

UPDATE 11:03 AM PT -- Amanda has already responded (and already deleted):

Before she called her ugly on Twitter, Amanda Bynes posed with Rihanna at the CFDA Awards in New York City ... way back on June 5, 2006.

The question is ...

Internal Affairs are looking into the allegations of sexual assault made by Amanda Bynes, an NYPD spokesman announced on Saturday.

Bynes has claimed that during her arrest, one of the officers sexually harassed her -- or as she put it, "He slapped my vagina."

NYPD chief spokesman Paul Browne confirmed the Internal Affairs investigation, saying, "As it would with any such allegation, regardless of its credibility, IAB is investigating it."

Amanda Bynes showed a TON of restraint when dealing with a paparazzo who clearly crossed the line with her this afternoon ... but she did call him "an ugly black man."

Bynes arrived back at her Manhattan apartment building and was met by a gaggle of paps waiting to catch a glimpse of her. Bynes covered her face and head with a scarf and some idiot photographer -- NOT ONE OF OURS -- continually kept trying to pull it off her head.

After first telling the guy "You can't touch me" several times, Amanda shot back, "Is it the ugly black one? Oh, there's another ugly black man."

When the photog tries to call her out for the racial remark, she responds, "It's just your face. It's not a black thing ... There's an ugly white one. It's not racist."

Bynes might be a little off her rocker, but she's the only sane person in this video.

Beware citizens of Gotham, Amanda Bynes is among you.

Not long after firing off a bizarre tweet of side of her arrest story, Bynes was picked up by a car service this afternoon and driven out of her NYC apartment building.

Our photog was only able to spot Bynes for a brief moment before she jumped in the tinted SUV ... and says the former actress ditched her blonde wig for a black one.

According to our spies, Amanda hit up a wig shop in the West Village. We're told she tried on a few blonde ones, but ultimately decided against purchasing any when the commotion from all the paparazzi became too much for her.

Amanda Bynes is now accusing the cop who arrested her Thursday night of sexual harassment ... saying on Twitter today, "He slapped my vagina."

Bynes just posted a long, rambling tweet trying to explain her version of the events that led to her arrest.

First off, she claims she only opened the window "for fresh air" and the cop was lying when he said she threw a bong out the window. She then explains, "He slapped my vagina. Sexual harassment. Big deal. I then called the cops on him."

Bynes' attorney did mention yesterday that Bynes was seeking to file a complaint against the NYPD for "inappropriate actions" by the department, but made no specific claims.

Back to the tweet ... Bynes claims she resisted before eventually being hauled off: "Then I was sent to a mental hospital. Offensive. I kept asking for my lawyer but they wouldn't let me."

She concludes, "The cop sexually harassed me, they found no pot on me or bong outside my window. That's why the judge let me go. Don't believe any reports."

Here's her tweet in its entirety, for your reading pleasure:

Amanda Bynes is not 5150 material, meaning she can't be picked up against her will and held for mental evaluation, at least not yet ... this according to multiple sources familiar with the situation.

Our sources tell us Amanda has not been diagnosed with any mental illness. Sources say her parents are worried there are signs she might be bipolar or schizophrenic, but Amanda has been unwilling to undergo psychiatric testing.

We're told her parents would like to create an involuntary conservatorship, similar to Britney Spears, but Amanda's conduct is not so over the line that a judge would take away her freedom.

Ditto for a 5150 psychiatric hold, which would allow authorities to put Amanda in a mental facility against her will for 72 hours for mental evaluation. We're told authorities just don't have the goods. In fact, Amanda was taken to a hospital after her arrest Thursday night and the shrinks didn't think an involuntary hold was warranted.

There's one other option to get a diagnosis. If Amanda is so out of it she can't understand the nature of the criminal cases that have been filed against her ... a judge can halt the proceedings and order a psychiatric evaluation. Amanda has been involved in 3 criminal cases in California recently, and there was NO effort to go this route. That's because she has always been lucid in court.

If you watch the video of Friday's court hearings, Amanda clearly understands what's going on and is actually sharp when answering the judge's questions.

Amanda Bynes has had a rough week. She's been arrested and charged with three crimes in New York City ... added to three crimes in L.A.. People are really worried about her, so we gotta ask ...

Amanda Bynes just tweeted something the cops clearly aren't buying -- she says she's drug free.

Amanda says, "I only smoke tobacco. I don't drink or do drugs." She adds, "I've never had a bong in my life!"

As you know, Amanda has been accused of smoking pot in her apartment and then throwing a bong out the window after police entered.

And there's more. Amanda says, "I need to get another nose job after seeing my mugshot!"

New York's finest returned to the scene of the alleged crime just a few minutes ago -- combing Amanda Bynes' apartment building for information and witness statements.

Law enforcement sources tell us ... NYPD cops got statements from the night doorman as well as 2 other employees, who were there when Amanda was allegedly smoking marijuana in the lobby and acting crazy.

We're told cops also went upstairs to Amanda's floor for more witness statements.

As we reported ... cops arrested Amanda after finding weed in her apartment. They also say she threw a bong out the window, allegedly to 86 evidence of a crime.

Amanda Bynes is back on the streets ... the judge released her on her own recognizance moments ago in NYC -- after she offered a hysterical excuse to cops for her alleged bong-tossing arrest.

According to cops, Amanda told them what she threw out the window last night was "just a vase." The official complaint was read in court.

Prosecutors requested Bynes be held in lieu of $1,000 bail. The judge instead chose to let her go without bail ... but gave her a stern warning that if she missed her court date in July an arrest warrant would be issued.

Amanda was escorted out of court by an officer ... and left, on her own, in a taxicab.

9:30 AM PT -- Amanda has been formally charged with attempted evidence tampering, reckless endangerment and marijuana possession.

8:52 AM PT -- TMZ obtained the criminal complaint from the incident ... which says a man in Amanda's building told cops he witnessed the actress smoking a joint in the first floor lobby.

The report says an officer went to Amanda's room ... and saw a bong on the kitchen counter.

According to the report, the cop -- wearing a "full police uniform" -- asked Amanda about the bong ... and that's when the actress flipped out.

Here's the cop's narrative -- "I observed [Amanda] grab said bong, run to the westbound-facing window, and throw it out the window where numerous pedestrians were walking on the 8 Avenue and West 47 Street sidewalks below."

Amanda Bynes had to remove her platinum blonde wig when she posed for her mug shot last night ... revealing a super short hair cut ... and Bynes didn't appear happy about it.

Bynes sported a scowl and a black shirt when she posed for the photo ... following a bong-throwing arrest in NYC last night.

The 27-year-old actress arrived to court this morning to face a judge -- wearing the wig again -- but it was clear she didn't want to be photographed.

Amanda Bynes has just arrived to court to face a judge about her bong-throwing arrest in NYC last night ... sporting the same clothes and platinum blonde wig she was wearing last night.

Bynes was led into the courtroom in handcuffs ... after spending the night in jail ... and asked photogs not to shoot her as she tried to hide her face.

As we previously reported, Bynes was booked for marijuana possession, tampering with evidence and reckless endangerment after cops say she chucked a glass bong out of her apartment window.

Amanda Bynes was arrested in her NYC apartment Thursday night for marijuana possession and throwing evidence out the window ... TMZ has learned.

According to law enforcement sources ... a building official called police after spotting Amanda in the lobby with a joint, acting erratically and talking to herself. We're told when cops arrived they knocked at her door and she let them in.

Our sources say when police saw the bong Amanda quickly tossed it out the window ... which fortunately didn't hit anyone on the street below.

Amanda, who was wearing a platinum blonde wig, was placed under arrest and went ballistic, yelling, "Don't you know who I am?"

She was booked for criminal possession of pot, as well as reckless endangerment and FELONY tampering with evidence.

Our law enforcement sources say Amanda was briefly taken to a hospital for psychiatric evaluation and then taken to the station for booking.

But the cop shop wasn't the last stop. A cuffed Amanda was then taken to night court just before midnight. She's still there in a holding cell, waiting for a judge. She should get a hearing sometime this AM.

This is priceless -- Amanda Bynes was flat-out rejected from a private jet flight in Jersey this weekend ... after trying to use GOOGLE as a substitute for her government ID, sources tell TMZ.

Amanda is denying anything happened -- but sources at Teterboro Airport tell us, Bynes (wearing a velour jumpsuit and giant glasses) showed up at the private jet terminal on Sunday for a flight to L.A..

According to sources, the pilot was checking passenger IDs -- it's a really small terminal -- and Bynes revealed her driver's license had been suspended ... and she had no other form of government ID.

We're told the pilot informed Bynes she needed a form of government ID to fly -- per TSA regulations -- and she then ordered him to Google her as proof, screaming, "I'm Amanda Bynes!"

The pilot called someone from the jet company to see if they could get some kind of exemption for her, but the jet rep was adamant ... no ID, no flight ... and that was that.

The private jet company wouldn't comment for privacy reasons.

Here's retired actress turned Twitter sensation Amanda Bynes showing off her God-given talents in one of her latest pics (left) -- and reassembled pop princess Britney Spears back during her unbeweavable 2007 MTV VMA "performance" (right).

Only one is currently under a conservatorship.