Stop! Or My Mom Will Shoot (1992)

"Detective Joe Bomowski's mom is in town for a visit. She did the laundry, washed the windows and scrubbed the floors. Now, she's gonna clean up the streets."

A tough police sergeant's mother comes to visit him, and promptly starts trying to fix up his life, much to his embarrassment. For his birthday she buys him a machine gun out of the back of a van, and begins to further interfere with his job and love life, eventually helping him with a case he's on.