The following information is from the Adventure Time comic book series. It may not be part of the same canon or continuity as the animated series.

The Creepy Finn & Jake robots were characters that BMO created in Issue 5 for Finn and Jake to do their chores while they went adventuring. As their name implies, BMO based them off Finn and Jake's appearance and made them look creepy, and it updates them to make them look creepier and creepier. In Issue 7, when Finn and Jake travel to the future, they learn that the robots turned evil when they were caught in the rain one day. After they were driven off, they built an army of evil robots that kept attacking Finn and his friends for fifteen years. Eventually the present Finn and Jake traveled back to their time and smashed the evil, creepy robots.