Little Man (2006)

"Big things come in small packages."

After leaving prison, dwarf criminal Calvin Sims joins his moron brother Percy in stealing an expensive huge diamond from a jewelry store for the mobster Walken. They are chased by the police, and Calvin hides the stone in the purse of executive Vanessa Edwards, whose husband Darryl Edwards wants to have a baby. Percy convinces Calvin to dress like a baby and be left in front of the Edwards' house to get inside the house and retrieve the diamond. Darryl and Vanessa keep Calvin for the weekend and decide to adopt him, while Walken threatens Darryl to get the stone back.