show one’s butt
v. phr.— «Showing his butt: A term used by officers to describe an inmate who is mouthing off or complaining about his treatment. As in: “That inmate was showing his butt.”» —“What the lingo means” by Adam C. Smith, Jo Becker St. Petersburg Times (Florida) Dec. 30, 1999. (source: Double-Tongued Dictionary)