By Big, I am talking like a one time hit of 6 figures or more. Like a big progressive slot, a really high bad beat poker, a gigantic keno long shot, or a royal on Caribbean Stud progressive. Something like that. Not a whale who wins big at 50k a hand blackjack. Would you need a SS card to claim winnings first and foremost for tax purposes? I know personally, I never carry mine. I also would imagine, if you were a low to mid roller who all the sudden won a huge take, the casino would really want to comp you and roll out the red carpet for the rest of this trip and for many visits to come, to try and recoup there money. Before my trips, I just like day dreaming of wondering through a casino drunk at 3 am, popping a few coins into a machine I never play, and getting a giant 6 figure windfall like Nick Papageorgio!