Wack the Bird Share definition Flag Male masterbation. Commonly used as a slang term describing the sexual acts of one, like "Beat the Meat." Dude, beat the meat is so out of style, use Wack the Bird. I Wack the Bird every time I see her. Wack the Bird by Paso Robles Slang March 9, 2010 Get the Wack the Bird mug.