The monkeys stay perched on top of the sides of the stairs leading up to the Pack-a-Punch Machine. If one is killed, another will replace it. They have very low health, and can always be killed by a single hit from any weapon, even in higher rounds.
When a power-up is dropped, they will howl wildly and one will run towards it. If a player gets a power-up before a monkey gets it, the monkey will attack the player once, and then run away. If the monkey reaches the Power-up first, they will run away with the Power-Up on its back, cycling through the various Power-Ups while glowing red. If the Monkey is killed before it can escape, the Power-Up shown when it was killed is dropped and can be picked up. If the Monkey escapes, the Power-Up is lost.
If the Monkey is killed before stealing a Power-Up or before it attacks a player, the player who killed it will earn 500 points, or 1000 points when Double Points is active.
Monkeys can be extremely useful if the player is skilled, as useless Power-Ups which are not needed can be used to get Max Ammo or Fire Sale.