A powerful punch executed during fights at Wal-Mart during the holiday shopping season, usually in a battle over the last $69 TV, $199 laptop, or other gift item. The frequency of Wal-Mart whacks reaches its pinnacle on Black Friday, as well as Christmas Eve.
Christmas Shopper 1: "Man, that guy got knocked out cold"
Christmas Shopper 2: "Yeah, he got a pretty good Wal-Mart whack right to the jaw. He's not getting that laptop now!"