Or Kemp is rubbing off on Manny! We've been doing the mid air collision celebration for the entire year. It's funny when Andruw does it because he doesn't get much air.
Before the homerun, Kemp went up to Manny in the dugout and rubbed his bat onto Manny's bat while Manny was taking slow practice swings. (I know that kind of sounds like sexual innuendo.) Kemp's next at-bat, he bombed one, opposite field.