NBC

Unlike the rest of the universe, Joan Rivers isn't all that curious about seeing how big Johnny Carson's penis really is in that sex tape -- because she says ... she's already seen it up close and personal.

Joan -- who guest hosted on Carson's "Tonight Show" for years -- said she and Carson had a "one night bounce" back in the day ... and he was hung like a horse.

Add Dave Chappelle to the list of people in awe of Johnny Carson's sex tape ... especially after we broke it down -- inch by inch -- for him last night.

Dave was actually in total disbelief when we told him about Carson's videotaped sex romp outside DBA nightclub in West Hollywood.

But you gotta see his face and hear his reaction when we tell him just how #blessed Carson was -- 10 inches by some reports.

Katharine McPhee's back with her hubby ... and their dogs.

It's been nearly 5 months since Katharine publicly sucked face with her married "Smash" director Michael Morris -- and sources close to the actress tell us, Katharine has been working hard to patch things up with her husband Nick Cokas.

Katharine and Nick are currently living apart -- but we're told they've been hanging out together more and more often recently ... Katharine even bought Nick a brand new Rolex as a make-good for the public humiliation.

Must have worked too -- we're told Nick's leaning toward taking her back.

What did the rooster say the morning after his wife cheated? Cuckoldoodledoo.

Jimmy Fallon's crushing his competition -- partially because NBC's making one helluva deal for celebs to come on his show, and stay off all the other networks.

It's the kind of hard bargaining ... expert negotiators can appreciate.

NBC is coming down like a hammer on celebs who want to get on Jimmy Fallon's show ... if they dare do a show on CBS or ABC ... they can forget about "The Tonight Show."

Sources connected to CBS, NBC and ABC tell TMZ ... the Peacock network believes Jimmy Fallon's ratings success gives them extreme bargaining power. They put the word out to celebs, agents and publicists ... if they want to be on Fallon they can't appear on ANY other network ... and not just shows that go head-to-head with Jimmy, but morning shows as well.

We're told NBC is saying the stars who go on Fallon are also allowed to appear on "Today," "Dateline" and any similar shows they air, but that's it.

A GMA source tells TMZ ... they've already gotten fallout from people they were trying to book.

Fallon is dominating late night .... crushing Jimmy Kimmel by bringing in more than twice the number of viewers.

"Biggest Loser" trainer Dolvett Quince still isn't happy with winner Rachel Frederickson's weight -- after she dropped from 260 to a scary 105 pounds -- but he tells TMZ, he's determined to get her healthy.

Rachel won Season 15 earlier this month ... but her dramatic weight loss shocked viewers, who claimed Rachel had lost TOO much weight, bordering on anorexic-looking.

And it appears Quince agrees -- he tells us, "We're going to get her healthy. She's going to be alright ... She's getting healthier every day."

Quince says he's still working with Rachel -- pro bono -- and has a plan to help her get better.

As if the men's USA Men's hockey team wasn't under enough pressure ... now a major porn company is making things worse -- by offering them 10 YEARS of free porn if they win gold.

... and not just any porn, HD PORN!!!

TMZ Sports has learned ... Brazzers says each player on the squad will get a month-long membership to the hardcore porn site if they beat Canada today ... and if they win the gold-medal game -- they'll get a full 10-year smut pass!

That's a whooooole lotta smut.

Don't screw it up Oshie.

Bode Miller says he's NOT upset with reporter Christin Cooper ... after she pushed him so hard about the skier's dead brother during a post-race interview yesterday, he broke down in tears.

Instead, it appears Bode is placing the blame on Christin's bosses at NBC.

The interview took place moments after Bode placed 3rd in the Men's Alpine Super G event in Sochi -- when Cooper kept asking questions about Bode's bro Chilly, who passed away recently from a seizure.

Bode broke down and cried -- ending the interview ... and almost instantly, the cyber-backlash began against Cooper.

But last night, Bode went to Twitter and wrote, "I appreciate everyone sticking up for me. Please be gentle w christin cooper, it was crazy emotional and not all her fault. #heatofthemoment."

He continued, "My emotions were very raw, she asked the questions that every interviewer would have, pushing is part of it, she wasn't trying to cause pain."

Here's where it gets interesting ... 'cause a short time later, he re-posted a tweet from a fan who wrote, "Bode. It wasn't her fault. It was the fault of @NBCOlympics producers. She was being told what to ask."

Subtle, but clearly he signs off on the fan's opinion.

Legendary newsman Tom Brokaw has revealed that he's been diagnosed with bone marrow cancer ... but says he's "optimistic about the future."

74-year-old Brokaw -- who's currently a special correspondent for NBC News -- was diagnosed with multiple myeloma.

According to a study by the National Cancer Institute, the 10-year survival rate for someone of Brokaw's age is 3%.

Still, Brokaw remains positive ... saying, "With the exceptional support of my family, medical team and friends, I am very optimistic about the future and look forward to continuing my life, my work and adventures still to come.”

He adds, "I remain the luckiest guy I know.”

“I am very grateful for the interest in my condition but I also hope everyone understands I wish to keep this a private matter.”

The eyes have it ... infections, that is ... and now, FINALLY, Bob Costas will take a night off from Olympics coverage so his peepers can heal up.

Costas tapped Matt Lauer to take over the hosting duties from Sochi Tuesday ... saying, "Reluctantly, I was trying to throw a complete game here, but we're going to have to go to the bullpen, and I don't know if you're aware of this tonight, but you're Mariano Rivera, at least tonight."

Bob started his Olympic coverage with what appeared to be pink eye -- it was red and swollen shut -- and after a few days it appeared the other eye came down with the P.E. too.

So, the question remains ... WHO KEEPS FARTING ON BOB'S PILLOW???

Don't expect Jay Leno to hijack "The Tonight Show" back from Jimmy Fallon ... because the ex late-night host swears he's done with TV ... FOREVER.

Jay was in West Palm Beach Florida -- but not to start his retirement. Leno was there to perform stand-up comedy just two days after his exit from "The Tonight Show."

Jay's answer may come as a surprise ... especially since he left the show in 2010 ... then famously wrangled it back from Conan O'Brien.

NBC is already distancing themselves from Jay Leno ... by erasing his name off the side of the building where he shot "The Tonight Show."

The Peacock network sent a team of painters armed with rollers and a forklift to white-out Jay's billboard -- just ONE FRICKIN' DAY after he signed off for good.

Here's what's interesting ... Jimmy Fallon's moving the show to NYC, so the net's not really under a deadline to change the signage before Jimmy takes over the reigns. Guess they just wanted to let Jay know that this "goodbye" is permanent.

Jonathan Martin says he HABITUALLY targeted with "vulgar" verbal attacks during his stint with the Miami Dolphins ... and finally left the team because he just couldn't take the constant harassment.

NBC has just released a teaser of Tony Dungy's big interview with the NFL player -- in which Martin never mentions Richie Incognito by name, but certainly implies he was bullied without mercy.

"I’m a grown man. I’ve been in locker rooms. There’s vulgar language used in locker rooms, and it doesn’t bother me – it’s the persistence of it."

He continued, "I wish I had more tools to solve my situation. But I felt trapped – like I didn’t have a way to make it right. It came down to a point where I felt it was best just to remove myself from the situation."

For his part, Incognito has adamantly denied bullying Martin.

As we previously reported, the two exchanged graphic taunts in text messages back and forth to each other during their time on the team together.

Skating legend Oksana Baiul has gone Chernobyl on NBC ... claiming the network screwed her over by making her sign a contract with a bunch of gobbledygook when all she knew was goulash.

Oksana is suing NBC, claiming the deal she made to star in "Nutcracker on Ice" was grossly one-sided and, as a result, she hasn't seen a ruble in profits.

Oksana made the deal when she was 16 and says at the time she had a feeble command of the English language and had no idea what she was signing. As a result, she claims the NBC nogoodnicks haven't anted up for the last 17 years.

Those crazy Ukrainians.

Gretl Von Trapp from the original "The Sound of Music" movie was left "mystified and disappointed" after last night's live remake on NBC ... and says Carrie Underwood TOTALLY BOMBED!!

Gretl a.k.a. Kym Karath met up with former co-star Charmian Carr (Liesl Von Trapp) to watch the special last night ... but their excitement deflated once "Sound" started.

During the special Kym tweeted, "Mystified & disappointed so far by SOM special. So far only happy with Stephen Moyer" ... then followed up by saying, "Must admit some scenes are actually painful to watch."

That's when Karath kicked things up a notch by roasting Underwood's performance adding, "Love Carrie Underwood but this role is just not right for her. She is lovely her voice is beautiful but acting is wrong."

For what it's worth ... the special brought in HUGE ratings for NBC with 18.5 million viewers.

Sam Champion is leaving ABC's "Good Morning America" partly because he and his hubby want to start a family and partly because of his thirst to become a honcho ... ABC sources tell TMZ.

Our sources ... who are extremely familiar with the situation ... say Sam has been chronically unhappy at GMA. We're told he wanted his own show -- badly-- but ABC execs weren't biting.

So, Sam jumped to the Weather Channel (which is co-owned by NBC), where he will anchor the network's new flagship morning show and also serve as managing editor.

Our sources say Sam wanted to be the one who replaced Larry King at CNN and he was shocked when he wasn't tapped. As one source put it, "Sam loves power, and becoming managing editor (of the Weather Channel) gives him that."

Oh, by the way, our NBC sources say Al Roker -- NOT a Sam fan -- is "pissed" his Weather Channel show will be Sam's lead-in.

Another reason Sam bailed from GMA is that he and his husband want kids and the hubby refuses to leave Florida (GMA is in NYC).

We're told Sam will be spending about half his time in Miami so the kids will know his face in person and not just on the tube. As for moolah, we're told its a lateral move. Our sources say Sam was pulling in around $2.5 mil at GMA and he'll be making around the same at the Weather Channel.

$2.5 mil for weather ... now THAT'S making it rain!!!