Back when I worked for Blockbuster, I was known to stick the Be Kind, Please Rewind stickers inside the DVD cases just to see if anyone would ever ask...
Of course, we did once have a little old lady bring her VCR in to the store to ask us to take it apart and get the DVD out of it. She seriously thought it would work.
And we also had a LOT of people who thought their PSX could play PS2 games, and people who thought their new Xbox could play PSX games.