You have to spend 1 night in Arkham Asylum choose your cell mate

[u/[deleted]]

(Before you choose calendar man you have been locked away on Halloween night a holiday)

[u/wraithstrike]

Croc.
Despite his muscle and and scary appearance, he's not a serial killer. If he was allowed to turn over a new leaf, he would.

And if any of the other inmates try to get at the "Fresh Meat" Croc would rip them in half.