Bad Santa (2003)

A miserable conman and his partner pose as Santa and his Little Helper to rob department stores on Christmas Eve. But they run into problems when the conman befriends a troubled kid. Willie and Marcus are professional heist men who use the Santa Claus routine as a cover to rob malls. Willie is an alcoholic and sex addict, struggling to perform the Santa routine. When they are hired at a mall in Phoenix, Willie's vulgar remarks catch the attention of the mall manager and security chief. Willie forms a bond with a naive and overweight boy named Thurman, who believes he is Santa. As Willie spends more time with Thurman, he starts to care for him and takes residence in his house. However, their plan to rob the mall is jeopardized when Marcus disapproves of Willie's actions and the mall security investigates. With a series of events, including encounters with bullies, a murder, and a police chase, Willie's life takes unexpected turns. In the end, Willie realizes the value of friendship and the true meaning of Christmas.