We've been lucky and taught him that poop goes in the big toilet, so we help him up on to that and hang out with him while he drops bombs. The little toilet is so he can do it by himself, he just needs us to empty it out.
The "singing toilet" operates by having two contacts at the bottom of the bowl. Liquid makes the connection, starting the song. I'd imagine diarrhea would make it "sing." :laughing :barf