This seems to be a Florida thing, but tree frogs get into toilets here.
Just waiting to get in.
Its usually the Cuban tree frogs, which are ugly little things. They fall into the plumbing vent and swim up the P trap in the toilet and stick to the side. I have had a few irate people call me about how they got a surprise while sitting on it in the morning. Don’t let this happen, get some Critter Quitters ate Homedepot.com or Amazon, or call one of our installers at critterquitter.com