A Minnesota tree trimmer allegedly killed his coworker by crushing his head with a hydraulic grapple while the two were “f—king around” and playing shadow puppets on the job, according to authorities.

Christopher Boone Crimmins, 34, has been hit with second-degree manslaughter charges for allegedly killing his coworker, Tyler Anthony Lynch, 26, in a bloody mishap during a tree-trimming job in Apple Valley on Aug. 20, according to the Dakota County Attorney’s Office.

Crimmins was on top of a boom and operating it from his seat as Lynch, of Royalton, was picking up tree branches on the ground, according to the criminal complaint.

The pair were “f—king around” and saw that the sunlight had cast a shadow of the grapple and the victim onto the street, Crimmins told officers, per the complaint.

Crimmins then jokingly maneuvered the hydraulic grapple to make it appear as though the shadow of the grapple was grabbing Lynch’s shadow — but was not paying attention to the fact that the grapple had inched toward his coworker’s head.

Crimmins then closed the grapple, horrifically crushing Lynch’s head, the filing said.

Lynch was found by officers lying on the ground with a large amount of blood pooled around his body and “a significant injury” to his head.

He was later pronounced dead, authorities said.

Lynch frequently posted pictures and videos of his tree trimming jobs and inspirational quotes on Facebook.

“I can tell we lost one of the best. RIP buddy,” one user wrote under pictures of his haul of lumber in the back of a truck.

Crimmins was cuffed and booked in the Dakota County Jail, where he has been held on $40,000 bail without conditions, or $20,000 with conditions, prosecutors said.

He is slated to return to court on Sept. 10.