Lena Dunham Backs It Up in Her Bootylicious Lip Sync Battle

By Nick Maslow

Lena Dunham sported athletic gear for her appearance on The Tonight Show Starring Jimmy Fallon on Friday. The actress said she chose the outfit because she "needed room to flex" for the duo's lip sync battle. Lena really wasn't kidding. At one point, she gave her best performance of Queen's "Fat Bottomed Girls," treating Jimmy to a front-row view of her booty moves. Watch the stars take on the challenge, then catch up on the latest viral videos, including must-see lip sync battles from the hit show on Spike.