Plot summary

The movie begins with Willie Soke (Billy Bob Thornton) working as a valet driver at a country club. He gets distracted when he sees a woman breast-feeding her baby, causing him to crash into a stand and knock someone over. Willie gets fired on the spot after arguing with his superiors.Willie's voice-over catches us up on the last few years of his life. He was not killed by the police at the end of the first 'Bad Santa' movie, but made a complete recovery and after his time in prison, he thought he got his happy ending by being with Sue, but his screw-ups caught up to him before she left him. He prepares to kill himself by sticking his head in the oven. When that doesn't work, he tries to hang himself. His suicide attempt is interrupted by Thurman Merman (Brett Kelly), now 21 years old and dumber than ever, still following Willie around even though he no longer believes he's Santa Claus. He even works at a sandwich shop now to fulfill his passion for making people sandwiches. Willy drops from the ceiling as he tries to stop his suicide.Thurman mentions that now that he's 21, he thinks Willie is going to "pop his cherry". Willie corrects him saying he would get it done by someone else. Willie calls Opal the prostitute (Octavia Spencer) to do the job, even though she isn't very willing. Thurman runs out of the motel room in a panic.Willie gets an unexpected visit from his old partner Marcus (Tony Cox), also fresh out of prison. He mentions there's a job that needs to be worked on for $2 million in Chicago. Willie isn't very willing to join Marcus since he tried to kill him on their last job 12 years earlier, but Marcus has apologized for that.Willie and Marcus arrive in Chicago for Willie to discover that Marcus wants to rob Giving Way, a charity foundation. To make matters worse for Willie, not only does Marcus expect him to put on a Santa suit once more, he discovers that one of the people working on the charity is his horrible mother, Sunny (Kathy Bates), who constantly refers to Willie as "shit stick". Willie punches her in the face and storms out, telling Marcus he has absolutely no intention of working with his mother.Marcus and Sunny later meet with Willie in her apartment to discuss the whole deal with their plan. Sunny claims she's got Parkinson's and has a really bad cough. Willie still refuses to work with her until Marcus tries to talk him into it. Willie finally decides that he'll do the job, but once it's over, he and Marcus are cutting Sunny off.Willie puts on the Santa suit to go out and collect money for charity. Another Santa comes by and thinks Willie is operating on his turf. Although he calmly tries to get Willie to leave, Willie accuses the man of being a pervert and starts beating the crap out of him in front of a crowd before Willie gets arrested. Meanwhile, Marcus is crawling through a vent to locate the safe when he comes across the charity's manager, Regent Hastings (Ryan Hansen), is having an affair with his assistant and is also embezzling money from the charity already. Marcus nearly gets found out when Sunny calls him and his ringtone goes off.After Willie gets bailed out, he must go to an AA meeting with Diane (Christina Hendricks), Regent's wife. Afterwards, she talks about her struggle with alcohol addiction and how it led her to do dirty things. Willie thinks she's asking for it and tries to put the moves on her, but she is disgusted and kicks him out of the car. Moments later, Diane drives up to him and admits she does want sex since she and Regent haven't been intimate in over a decade. Willie then does it with Diane behind a dumpster in an alley. They don't know they're being followed by Dorfman (Jeff Skowron), a Giving Way security guard who Regent hired to take pictures of the two.Marcus tries to get a key to the charity's safe by attempting to seduce Gina (Jenny Zigrino), another security guard. After taking her out for a fancy dinner, Marcus tries to go to bed with her, but she turns him down because of his height.Willie meets up with Diane and they do it on some Christmas trees. He asks that she call him Santa like Sue did, so she does.Willie reluctantly starts to bond with Sunny as she tries to get close to him again. He notices how bad her cough is, so he steals some medicine from a pharmacy for her. Sunny later gives Willie a gun in case Marcus tries to double-cross him again.Sunny later gets Willie to have sex with Gina for the keys since he has a thing for big fat girls. Gina is satisfied and Willie takes her keys. Marcus becomes upset after learning this and tries to attack Willie, but Willie manages to slam him onto a table.Thurman has traveled all the way from Arizona to Chicago to be with Willie after learning that he went there himself. Willie is utterly displeased to see this and tries to leave Thurman somewhere alone before feeling guilty and deciding to drop Thurman off at a shelter full of degenerates to get him out of his hair. Thurman later goes by the charity and sees the children singing. He manages to get the director to let him sing as well, and she gives him a Santa suit to put on, which excites him.Willie, Marcus, and Sunny prepare for the robbery as the charity is holding its event where the children are singing. Sunny takes out the lights while Willie and Marcus try to open the safe. Willie stops and sees Thurman getting up to sing in his Santa suit. Willie is surprised to see that Thurman has a lovely voice, and it even moves him to tears. When Willie and Marcus finally open the safe, Marcus reveals he really was trying to double-cross Willie. Willie gets his gun and gets the money out of there before the guards come after them.Willie and Marcus bring the money outside, but Sunny reveals that she was going to take the money all for herself. She shoots Marcus in the chest and runs him over with her van as she tries to get away. Willie goes after her and chases her into SantaCon. Willie manages to find her, and Sunny ends up shooting Willie as well. He grabs her bag and lets all the money fly out. Sunny tries to shoot Willie again, but Thurman shows up and jumps in, getting himself shot in the butt. The cops arrive and arrest Sunny while the medics take Willie and Thurman away.Willie wakes up in the hospital getting a handjob from Diane, meaning he finally got his "happy ending". His voice-over reveals that he tipped the cops off about Sunny, meaning he managed to avoid jail time once again. Regent's embezzlement scheme was discovered and he was booted from the charity. He has decided to keep Thurman around as company since he has decided his new family is way better than his old one. Willie now works as a janitor in the hospital, and he finds Marcus's room. He considers smothering him to death, but Willie gets his revenge by teabagging a helpless Marcus and posting pictures on Instagram.