At a Lakers game with pals in LA’s Staples Center, David Spade saw his face flash on the jumbo video screen and heard the crowd cheer — but turned away modestly and acted cool! The cheers suddenly got louder, so Spade finally stood to take a bow . . . and was immediately yanked down by a pal, who yelled, “Siddown, man! They’re not applauding you — they’re hollering for the girl behind you who just flashed her bare BOOBS!” Spade was embarrassed — and BUMMED because he’d been so busy being “cool,” he never got a peek at the chick!