A Pennsylvania son tired of his mom’s late-night rendezvous called the cops on himself and allegedly admitted to killing his mother’s romantic partner while the couple was “hooking up” in the victim’s truck on Saturday.

Dylan Lang, 24, was charged with homicide after he snapped when he found his mother fooling around with her lover, 55-year-old Robert Hagen Jr., and shot him in their driveway, police said.

Lang claimed his mother and Hagen were having sexual relations for several days. He told cops he finally spun “out of control” after the pair went out drinking on Friday evening and came back to continue their romp sesh outside the family home early in the morning, according to authorities.

Lang allegedly stormed outside with a 9mm handgun when he noticed the pair “hooking up” in Hagen’s truck, which was parked in the driveway of the family’s Jackson Township home — which he shares with his mother, her ex-fiancé, and two other relatives, police told Fox 5.

The fired-up son allegedly tried to point the firearm through the driver side window, but it wasn’t opened far enough. So, he shattered the rear window and allegedly fired two shots at Hagen through the back of the seat.

Hagen was fatally struck in the upper torso while attempting to back his truck out of the driveway. He lost control and the truck wound up rolling right into the front yard, police said.

All the while, Lang’s shaken mother, who was still inside the vehicle with Hagen, was reportedly screaming “You shot him!” at her son.

Lang, too, reportedly phoned 911 and told dispatchers, “I just shot someone in my driveway. I f–ked up.”

When police arrived at the grisly scene shortly before 4 a.m., they found Hagen inside the truck bloodied “with his pants around his ankles,” the outlet reported.

Lang is being held without bail at the Cambria County Prison on charges for criminal homicide, aggravated assault and reckless endangerment. A preliminary hearing is scheduled for Oct. 27.

State police were called to lead an investigation into the shooting.