A group I was DMing was traveling the high seas when a ship full of Darfellan pirates attacked. In the heat of battle the captain of the ship was thrown overboard and the party soon discovered that just off the ship was a huge shark circling(The poor captain had no chance). The rest of the encounter was them playing king of the hill trying to push people off while staying on the ship. Since I'm kind of a dick and want every encounter to be as close to a TPK as possible without actually killing anyone the ship was basically going to crash into a reef and sink. Since I knew nobody took prof (sailor) it was funny to see the sort of panic that began to set in as they all searched their sheets (I would have let them make checks without it, but they didn't even try). One of them started laughing and asked if his familiar (a racoon) could steer the ship. I said "Fuck it if you roll a nat 20 I'll allow it since it's funny". Of course somehow he did, and they sailed into town with Captain Furbeard. I ended up giving his familiar a permanent proficiency bonus to sailing.