Justin Bieber Flashes Washboard Stomach, Gets Very Close To A Mannequin On 'Fallon'

No, he did. A mannequin head, to be precise. And really got into it as well, even though Fallon advised him not to fall in love with it. There's a hilarious video of it right below. It's NSFW and kind of ... weirdly, grossly compelling.

[Photos: Getty Images]