Justin Bieber strips to his underwear at "Fashion Rocks"

Nothing gets between Justin Bieber and his Calvin's. Not even his other clothes.

The singer stripped down to his underwear on stage Tuesday night during the "Fashion Rocks" show.

As Bieber and model Lara Stone were introducing performer Rita Ora, the crowd could be heard booing. The 20-year-old singer then said, "I actually don't feel comfortable unless I'm in my Calvin's. So, what's up? Is that cool?" before taking off everything but his Calvin Klein boxer briefs and striking a few poses.

That, it seems, got the crowd back on his side -- some cheers could be heard as he removed his blazer, pants and tank top.

"Just stripped on national television hahahaha it wasn't planned," Bieber wrote on Instagram.

On Twitter, he added, "Good times tonight. Thanks for having me tonight #FashionRocks. #mycalvins :)"