A childhood belief about weeing and pooing

It was actually not until I was pretty well grown up that I first encountered the phrase "to take a dump" meaning to poop. For a while I didn't know what was meant. I thought the phrase would mean like falling out of one's chair, or falling off a bicycle or a sled, etc. I finally was corrected in a moment when I was made to feel stupid when the phrase was used and I responded as if it meant someone had fallen onto the floor. Since then I've tried to make a joke of this whole awkward learning experience. Like once recently at a Christmas exhibition, I sat down at the eating area and found I was sitting in a very rickety chair. On inspection I found the chair seemed to be about to fall apart. So I hung a sign on it reading, "Caution. Chair broken. Sitting not recommended. You might take a dump." I hoped someone might find it riotously funny, but I never observed any consequences.