Comedy involving a contract killer [closed]

I once watched a Hollywood movie. A contract killer and a man who was ditched or thrown out by his girlfriend or wife settled in two side by side hotel rooms. The killer is getting ready for his job by fitting his telescopic gun through the window when the sad stupid man is knocking on the door of the killer, to get some sympathy.

Eventually the sad man got interest in this killing and in the gun. While the would-be victim entered the hotel (pathway visible through this window), the sad stupid man fired the gun. The victim had a security cover. He himself was dressed as a bodyguard while one of his bodyguard was dressed like him. But the sad man killed that "body guard" for his lack of skill and thereby fulfilled the contract. What is this movie? Please help.

identify-this-movie comedy

Best Answer

Seems you're after Billy Wilder's Buddy Buddy from 1981 with Jack Lemmon and Walter Matthau.

Hitman Trabucco has been hired to eliminate Rudy "Disco" Gambola before he testifies against fellow members of the Mob, but completing the contract becomes problematic once he encounters suicidal Victor Clooney, an emotionally disturbed television censor staying in the room adjacent to his in the Ramona Hotel in Riverside, California.

The hitman (Matthau) can't do his job so Victor (Lemmon) does it instead but shoots a cop by mistake. Then it turns out that the cop was the target in disguise. It was based on a 1973 movie written by Francis Veber (and based on his play) which had several adaptations. It's also the last film Wilder directed, though he didn't exactly go out on a high note with this one and was embarrassed with it. Here's the trailer: