The US star, who plays mad-as-a-box-of-frogs Alan in the series of films, somehow managed to look totally different despite only shaving off part of his beard and running a comb through his hair.
Before and after: Zach Galifianakis
Not even the fact that we'd seen that shirt and tie before could help us identify him.
Oh, and if you're also wondering (like we were) why he's stood in front of a backdrop branded with 'Very Bad Trip 3', that'll be what the Frenchies are calling 'The Hangover 3'.
Maybe they simply don't get them.