A furious bison knocked out a motorcyclist who came too close to her calf — and added insult to injury by pantsing her too, startling video shows.

The beast attacked the 54-year-old Iowa woman at Custer State Park in South Dakota on Wednesday, catching her belt by its horn and swinging her around violently, according to a report by the Custer County Chronicle and shared on the sheriff’s office’s Facebook page.

“She was apparently saved when her pants came off and she fell to the ground unconscious,” the report said.

The woman was flown to a hospital on a helicopter and is expected to recover.

The frightening incident occurred while thousands of motorcyclists are in the Black Hills for the Sturgis Motorcycle Rally about 60 miles from the state park.