Here's one from a few years back that I'm still struggling with.
Guy on third, one out. On a swinging third strike, the catcher boots the ball after it smacks in and out of his glove and rolls behind him (it's bad high school baseball).
Guy at the plate goes to first, guy at third goes home. Guy coming home is out catcher to the pitcher at home while the batter reaches first safely. If the catcher had chosen to go to first, he would have had the guy there as it took everyone a second to realize what was happening.
Obviously the guy coming home is out 2-to-1. But how does the guy reach first? K-PB, since the catcher booting it allowed the guy to advance, or K-FC, since the other team could have gotten him out at first and did record an out on the play?
The next batter walked, then the guy after that homered, so the original batter in this scenario did end up scoring in the inning. I hate bad high school baseball.