No joke:

Cubs first baseman Anthony Rizzo fell to a knee while swinging at a Jordan Zimmermann curveball in the sixth inning of a game against the Tigers on Tuesday. After connecting with the pitch, Rizzo fully topped over onto his hands and knees as the ball cleared the right-field wall at Comerica Park to give Chicago its first run of the game.

Presumably Rizzo would happily accept whatever embarrassment comes with falling down anytime it comes with a home run, but rare is the swing that both drives a ball out of the park and fells its progenitor.