I think reading this thread jinxed me.
I had seen relatively few pranked toilets, and not in a while. But one of my Sims has made friends with a Goofball. She surprised my Sim with a visit one afternoon, promptly went into his downstairs bathroom, and...you know what happened.
The same Sim-afternoon, my Sim was relaxing at a cafe. His Bladder need went into the yellow, so he went upstairs to use the toilet, and...you know what happened.
After my Sim repaired the toilet--his Handiness skill got quite a boost that day--I looked around to see if any likely pranksters were around the cafe. Sure enough, Prankster Woman was there, chatting up the barista as if nothing had happened.
I used to go into CAS to cut down on the Kleptomaniac population of my Simsworlds. Now I might have to look for Goofballs to tone down, or try @83bienchen 's mod.
Will Erratic Sims pull the same annoying stunts constantly, or does their Erratic nature cause them to try different dumb things? I want a few mischievous/ornery Sims in my world.