swack Share definition Flag Swack is basically another word for fuck. This word originated in San Diego, where lots of guys use it. GUY 1: Look at that ass over there, would you SWACK? GUY 2: I'd mos def SWACK that. swack by Matt December 28, 2004 0 0 Get merch Get the swack mug. Buy Now — $32.95 See more merch