Once turned around in The GAP to find my then three year old daughter dragging someone else's baby out of the store.
The baby’s mother was very understanding, and I think that was possibly because she had also turned her back on her own kid for long enough that he was kidnapped.
So, in the spirit of parental solidarity, if you should chance to look up and see some little rascal doing something you are pretty sure his mother doesn't know about, snap a picture, and show her what she missed.