Grumpy was a member of a crew hired by the Joker to rob Gotham National Bank. He and Chuckles drove to the front of the bank, picking up another member of their crew on the way who was the Joker in disguise. On the way Grumpy complained that the Joker was sitting it out and still would take a share of the money they got. The three men then burst in through the front door and held everyone at gunpoint, handing out live grenades so they couldn't move their hands.
The bank manager then killed Chuckles with a shotgun and shot at the other two intruders. Grumpy checked with his remaining accomplice that the manager was out of ammo, before jumping up, but got shot after the Joker apparently miscounted. Grumpy then went to the vault where Happy had opened the safe, so Grumpy (on orders given to him previously by the Joker) shot and killed Happy. He then loaded all of the money into bags and piled it in the bank lobby. Realising that all of the crew members had orders to kill each other, Grumpy drew his gun on the Joker as he suspected he was next. The Joker responded by saying that he would kill the bus driver, and as Grumpy became confused a school bus smashed through the wall of the bank and killed him.