Justin Bieber Justin Bieber

Justin Bieber stripped down to his underwear during a New York Fashion Week event Tuesday — and was booed.

Justin Bieber: A timeline of bad behavior

At the Calvin Klein Fashion Rocks event at Brooklyn's Barclays Center, the 20-year-old singer took the stage with model Lara Stone to introduce Rita Ora. The crowd responded with a loud chorus of boos, but there were at least a few Bieber fans in the audience, who managed to drown out the boos with ear-piercing screams as the legally challenged singer ditched his blazer, shirt and pants. Eventually clad only in red and black Calvin Klein boxers, Bieber noted that's the only way he's comfortable.

Bieber later tweeted a tasteful Vine zooming in on his crotch, with the caption: "Grandma always said kill 'em with kindness...and then strip on live national tv. Lol."

Check out his striptease below: