He helped the Joker in a crime spree by robbing people that were under the effects of Joker venom. He also robbed stores with an unnamed henchman of the Joker. He wore a special clown mask that protects him from the effects of the Joker's venom. The Joker sent Jest and his unnamed partner to get Batman. However, Batman removed Jest's mask and his partner's too thus making them breath in the gas and became vulnerable to the gas effects which caused them to laugh. It is unknown what happened to Jest and his partner afterwards.