I was supposed to do an U18 game one Sunday, turned up at the park and no U18's team, game had been called off and I wasn't told! There was an U14 match due to kick off at the same time and they didn't have an appointed ref due to shortages, so they asked me to do their game for them, which I was happy to oblige.
I had more foul throws than fouls in the game and after the match both managers thanked me for calling them out, because whilst they practice them at training, because they end up with parent referees for most games, they never get penalised in the games.