Aubrey Plaza's deadpan humor never fails to get a laugh [1], and the hilarious story she recently told to Jimmy Kimmel about shooting a graphic sex scene with her Dirty Grandpa costar Robert De Niro [2] was no exception. After calling her sex-obsessed college coed character "terrifying," the actress went on to describe the pair's scene, which took a whopping nine hours to shoot. "There was a lot of interesting stuff that went down, you know," she said. "I'd try to get in there, and suck on his nipples, and he was like batting me away, and I didn't know if it was in character or not, because you never know with him." Watch the funny video above, then check out photos of Aubrey rocking a bikini on the movie's set [3]!