I don't know if you can really tell from this still photo, but Max has begun violently splashing in the bath the last few scrubbing sessions. I invariably end up just as wet as he does, despite my place on the sidelines of the bath. You can't really see the waves he is creating, and I have forbidden photos of my bedraggled, drowned-rat self to be used as evidence, so you will have to rely on his face to really experience the magic. If you look closely, you can see that his eyes are slitted almost closed, so that he doesn't get water in his own eyes. Since he is in the 98th percentile for height, his eyes are far enough away from his hands that you can imagine the strength of the wave that would necessitate this kind of caution.
His other move, which he can be seen preparing for here, is a sort of modified cannon ball. Gripping the bar along the side of the bathtub (which I still see no use for, other than Max's sinister applications), he will stand up, get all the way up to tippy toes, and then sit down abruptly, causing a bum tsunami to rock the bathroom.
This photo was taken immediately before Chelsa was pulled into the bath by Max, where she disappeared down the drain and has not been heard from since. Max is believed to have sent down his bath boat as a life preserver, so there is reason to hope that Chelsa remains among the living. Teams of tiny spulunkers are investigating.