You've probably been seeing headlines about a Bradley Cooper lookalike "terrorizing Sundance" last week. Well, this is how he did it:
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Meet Matt Katzenbach.

Cradley Booper on the loose!
"Wear a suit jacket, but no tie. Don’t tuck in your shirt. Look like you slept in the clothes you’re wearing, but also like you could be sitting front row at a Prada fashion show in them (we know, it’s a tricky balance)."
"Walk up to one of the caterers passing around hors d’oeuvres, and crouch down a bit and say, “How are you doing tonight, hon? You O.K.?,” and then when she starts to answer, sort of absentmindedly look around the room."
"Drop David and Jennifer and Sienna into conversation, with as much verbal italics as possible."
"Every once in a while, jump up-and-down seven or eight times. If anyone gives you a weird look, just smile and nod your head at them. (They will smile and wave back.)"