LOL...too funny!
Angharad, I had something similar happen (not with the toilet) with my pet bird. She's a very curious creature and will inspect just about anything within her reach.
I was preparing some water for making spaghetti. I filled the stainless steel pot almost full. The bird (Sunshine) was on my shoulder (not the song, silly) curiously looking down over my shoulder.
Occasionally, I will have her hop on to my finger, and place her on one of her favourite perches. I go to the washroom for a moment, and I don' t know how long it took, but I returned to the kitchen to find something splashing around in the pot, and having a ball doing it.
Sunshine was diving into the water, and rubbing the water under and over her feathers. I nearly died, because I thought she had hurt herself. But on the contrary, she was having the time of her life.
Dumped the water, grabbed the bird, a towel, and proceeded to blow dry her (which she loves). And yes, the little monster, LOVES spaghetti.
I'm sure a cat, under any circumstances would be quite a sight. That was hilarious Angharad.