This really made me laugh...
Was at the library with DS (4yo). He chose a book (on cars again) and we went to check it out.
He wanted to scan it himself, but the scanner was too high so the lady who works there said 'you can stamp it for me instead'
She passed him the book and was holding out her date stamper.
DS looked a bit confused, but carefully placed his book on the floor, looked at me and lifted up his foot to stamp on it. I stopped him just in time