Hand gesture used in sketchy or shady situations often performed while announcing "shady tree" or any accusation of sketchiness. To perform the Shady Tree, the left hand is made into a fist, thumb-side up, and the right hand is held open, palm down. The palm of the right hand should be placed atop the left fist and the outstretched fingers of the right hand wiggled in a manner similar to that in jazz hands.
A: ...and then he asked her to go behind the shed.
B: *shady tree* Sketchy.
A: I know, right?