Janitor Monkey

The Janitor Monkey is a special agent that can be purchased with money during a game. It costs $1000. In the next Bloons Tower Defense game, some levels will have trash blocking you from putting towers in certain spots. You can purchase the Janitor Monkey to clear all of the trash within its range (it's the only tower that can be put on top of trash). It takes the Janitor Monkey 5 rounds to get rid of the trash, and then it leaves.