The act of taking both of your hands and forming gun motions and winking with both of your eyes.
This is used with a sexual reference.
College guy #1: Oh damn she's so fine
College guy #2: Dude, dwink at her
*College guy #1 dwinks*
Hot girl: OMG I want to do him. I am so flattered because he just dwanked at me.
College guy #1: OMG come home with me.