Amanda Bynes -- Fashion Disaster During Court Hearing

Amanda Bynes rolled into a New York courtroom today dressed more for a rave than a court hearing -- sporting an aqua-colored wig, sweatpants, a tank top ... and sneakers!

... and no one was surprised.

Bynes was in court to fight allegations she threw a glass bong out of her NY apartment window back in May.

According to police, Amanda threw the bong out of her window before they arrested her, but she has denied the accusation ... in fact, she says the arresting officer sexually assaulted her by slapping her vagina.

She also said cops entered her apartment illegally.