I was at the co-op one afternoon and stopped to help a customer with their bike... told them, with all seriousness in my voice, that the rear shifting thingamajig needed some transmogrifiation and he asked if there was anyone who actually knew how to fix their bike around.

The other mechs were laughing their asses off... I am the senior mechanic and by the time folks had stopped laughing I had got the derailleur working the way it was supposed to.

The customer realized that I was just messing with him and got a good laugh out of it too.

Every once in a while we find that someone has a frim fram in their zim zam or that their veeblefetzer needs re-greasing.