Had a famous Aussie football team onboard one day.
As usual, there always has to be one in every group!
After several requests to return his tray table to it's stowage position ( at every request he obliged immediately ), however, each time I passed by it was down again.
I stood at his row and in front of his whole fellow team mates, said " Sir, you obviously don't have trouble getting it up, it's keeping it up that's the problem! "
The whole team roared with laughter.