La Doof Kitton is concerned about this scary box of water and why mom subjects herself to it...so he involves himself in it's filling. (And then, since he has made it a habit to consider falling in, he gets kicked out of the bathroom while mom takes her soak. (because as we all know, a cat falling into an occupied bathtub leaves one with legs that look like they lost an epic battle with a blender.)
There is a slow progression...from side-of tub sitter...

to "stalking the razor" kitteh

to "balancing precariously kitteh". He is quite talented at balancing (there are zero feet on the sides of the tub in this one):

And it tends to end with "ooh, lookit, I just dumped in more bubble bath for ya ma!"
(and this would be the point at which he is escourted out of the bathroom and the door is closed.)