Bathroom behavior

So whenever I take Lincoln to pee, I always make sure he shakes off his drips so as to avoid a mess (you all know how messes make me twitch). Sometimes to facilitate this, I will pat his bum a couple times to clear the lingering drops. He has taken this upon himself now, when he goes to the bathroom alone, and will spank his bare bum 2 or 3 times - with vigor - when he's done peeing . . . you know, just to get the drips off. Seriously . . . you can't help but giggle.