That chick that dressed up as Kate Upton at the Pink Taco Halloween party on Sunday? That was Kate Upton.
From the New York Post:
Kate Upton managed to go incognito at Sunday's Halloween Costume Contest at Pink Taco on Sunset Boulevard -- by dressing casually and covering up her famous body. Looking low-key in jeans, a T-shirt and a trucker hat, a source tells us, the busty Sports Illustrated Swimsuit model fooled partygoers who mistook her for a look-alike. "Someone finally realized it was the real Kate," says the spy.