Buddy Buddy (1981)

Walter Matthau plays a professional killer going by the name of Trabucco, who is on his way to rub out gangster Rudy "Disco" Gambola, set to testify against the mob. As Trabucco heads off to a hotel across the street from the courthouse where he plans to set his hit, he runs into the depressed Victor Clooney, who laments the fact that his wife has left him for the head of a weird Californian sex clinic. Trabucco keeps walking and sets up his rifle in a hotel room. He is disturbed by Victor trying to hang himself in the adjoining hotel room and tries to prevent him from killing himself by restraining him, but Victor breaks loose and climbs onto the ledge of the hotel window. To get Victor to come back in, he agrees to drive him to the clinic to see his wife. The two go to the clinic where Victor's wife Celia informs Victor that she is in love in the head of the clinic, quack Dr. Zuckerbrot. When Victor finds out that Celia is filing for divorce, he heads back to the hotel to kill himself, with Celia and Dr. Zuckerbrot in pursuit. Arriving at the hotel, they plan to inject Victor with a sedative but stick Trabucco with the needle instead. Trabucco reveals to Victor his assignment to kill Rudy, and Victor tries to help him with the killing.