Always a chance that a house guest brought along individually wrapped wipes.

I remember going camping one time with my parents like 15-20 years ago. Some family friends also came along with their daughter and we all stayed in my parents trailer that can sleep 8 people.

Something clearly stated to the girls was that feminine hygiene products get wrapped and go in the garbage can, not in the toilet of a trailer.

Sure enough my dad and I go to empty the tank when we're done camping, and we can't close the valve back shut afterwards, something is blocking it. So my dad has to go elbow up into the pipe and pulls out a bloody tampon from their friend's daughter.