Shag Up Share definition Flag A mash-up of shack up and shag, meaning "sexually-active cohabitating" I knew it! Nikita was going to shag up with Micheal sooner or later. Shag Up by maddoc23 May 14, 2011 0 0 Get merch Get the Shag Up mug. Buy Now — $32.95 See more merch
