Unicorn's caged monkey is a monkey cage containing the monkey that was on a unicorn's back during the 2021 Birthday event. To catch the monkey, the cage must be placed near the unicorn with a monkey on its back or used on it, at which point a cutscene will play of the monkey being lured into the cage.
The caged monkey cannot be deposited into a bank. If players try to bank it, the chatbox will state "A magical force prevents you from banking this item!" On death, the caged monkey is always deleted from the player's inventory.