Qbac Share definition Flag Used as a secret code word to talk about material found after hacking into someone's computer and finding dirt on them. omg I can't believe Qbac, its fuckin disgusting shit, I can't believe she's a fuckin lesbian. Qbac by Shane Dobson May 22, 2008 0 0 Get merch Get the Qbac mug. Buy Now — $32.95 See more merch