Same as a normal sock surprise, however, it is done with a used sock and going commando. The resulting odor can be used as either an aphrodisiac or as a way to disorientate your new friend.
guy 1: Did you pull off that sock surprise last night?
guy 2: You bet!...but I did a dirty sock surprise. As soon as I pulled that magic out and she caught a whiff, it was as if candles lit the room and kenny g played played a single breath solo...she didn't care about the size of my penis anymore, love was in the air!