Irwin Sure-Win Share definition Flag n. a bet won against impossible odds. The expression is derived from the untimely and unlikely death of the late Steve Irwin. Jonathan pulled an Irwin Sure-Win at the casino last night. Irwin Sure-Win by tneveca August 29, 2009 0 0 Get merch Get the Irwin Sure-Win mug. Buy Now — $32.95 See more merch