The 26-year-old actor rocked a long brunette wig, headband and floral dress to play "Brittany" in the sketch, where he snaps selfies with his new smartphone and Twerks with his friends to Lil Jon's "Turn Down for What?"
And of course, they play their signature game to decide what's cool and what's not. They save the best for last, when Jimmy flashes a picture of James Franco, who they all decide definitely warrants a major "Ew!"
Zac clearly had a good time playing a girl, Tweeting: "Mwaaah @JimmyFallon! Love, Brittany," afterwards, with a link to their silly skit.