So I don't want to sound like "my players are not playing right" but they keep doing stuff that is very metagamey and just not what their character would do. They just finished their first encounter with a group of pirates, they were lost in the woods and thirsty, plenty of wildlife and berries to eat. They found water on the pirates and then they cooked and ate the pirates.... They keep trying to strip off all clothes and weapons from their enemies to sell. What do I do? How do I roll with it? How do I stop it or prevent it from being as good as it is?

Edit: Thank you all for the amazing feedback, I wouldn't have thought about much of the stuff you said.