As Giuliana then said to him: What?
Well, a fall refers to the end of a wrestling match, so apparently Clooney was referring to his lady's athletic prowess, which she acquired as a brutal(ly good-looking) member of the WCW and WWE circuit.
"She can kick my ass," Clooney explained simply—and out of Keibler's ear-shot. Oh, and he admitted that she's really nice, too.
Keep the heartfelt details coming, George, we love 'em!