This prank was criminally bad.

According to authorities, a man from South Carolina reportedly hid in his ex-girlfriend’s shower and when she returned home early on Sunday, he came out holding a knife in what he claimed was an attempt to “prank” her and “lighten the mood.”

Jackson Collum Arnold, 25, used a pair of his ex’s bike shorts and a hat to cover most of his face, but was naked from the waist down as he gave his former girlfriend a paralyzing scare around midnight, Charleston cops alleged.

The victim accused Arnold of holding a knife to the side of her head, and when she pushed him away, he pretended he was slicing her throat, though the knife didn’t touch skin, according to a police report obtained by news outlets.

He then allegedly choked her before the victim yanked the shorts off the suspect’s face and discovered the man attacking her was her on-again-off-again boyfriend, the police report states, according to WCBD.

The victim told police she feared for her life and thought she was about to be raped inside her garage apartment before she saw it was Arnold.

But the lousy jokester claimed to authorities he only snuck into her home to “surprise” her and “lighten the mood” after the pair got into a fight over text earlier that night, according to the police document also reported on by WCIV.

His underwear was reportedly found inside the bathroom by officers, though he did have a pair of jeans on when police reached the scene, thanks to a 911 call.

Arnold allegedly went to great lengths to carry out the criminal ruse, including parking several hundred feet from the property the victim shares with her family, who live in the house attached to the garage.

He also kept his cell phone at home because he might have been sharing his location with her using the Life360 app, according to the police report.

He was booked early Sunday on charges of assault and battery, first-degree burglary and possession of a weapon during a violent crime.