The Canadian pop star received the frosty reception as he introduced Rita Ora at Fashion Rocks.
As he walked down the catwalk with his co-presenter, model Lara Stone, he said: "I actually don't feel comfortable unless I'm in my Calvins. So, what's up? Is that cool?"
As he removed his blazer, tank top and trousers and stood in his boxer shorts, the boos turned to cheers as the crowd pulled out their smartphones to record the moment.