Don't try this at home — or in jail.

An inmate at the Merced County, Calif., Main Jail had a homemade knife surgically removed from his body cavity last month, according to Merced county Sheriff's officials.

He now faces concealed weapons charges.

The inmate, 19-year-old Rance Johnson, approached corrections officials Nov. 18, complaining about an item stuck inside his rectum, causing pain, according to Deputy Tom MacKenzie.

Even worse, Johnson told deputies the improvised weapon — known in jailhouse slang as a "shank" — had been inside his body for three weeks.

He was taken to an emergency room in Modesto, and the 5-inch-long plastic shank was surgically removed, MacKenzie said.

"The taxpayer money does cover actual stupidity; hence this guy did have to have this surgically removed," said Sheriff Mark Pazin. "It's unfortunate, but it's a mandated surgery."

MacKenzie said Johnson told investigators he had no idea what the item was, that he'd found it in an interview room and tried smuggling the weapon by inserting it into his rectum. The item was wrapped inside tissue paper and placed in a sandwich bag before it was inserted, MacKenzie said.

Read more at MercedSunStar.com