Mark Duplass on Being a Dick to Ben Stiller

When we sat down Humpday heroes Mark Duplass and Joshua Leonard, Duplass was on a career high: He'd just held a successful first screening of an untitled Fox Searchlight comedy he'd directed starring Marisa Tomei and Jonah Hill ("They're, like, amazing as performers), and he was eager to talk about Greenberg, the upcoming film from Noah Baumbach (The Squid and the Whale) in which he stars opposite Ben Stiller. So how did the mumblecore leading man and the Night at the Muesum star get along?