this is not so much as "says" thing its more of a "done" thing.

When my eldest son was about 3 or 4 we went to B&Q and as we were talking to the assistant he disappeared... all parents will know this is a heart stopping moment which ends up with you running around the shop looking for him.

we finally found him, it turned out he just needed the toilet and was sat on the shops demo bathroom having a shit in the show toilet