It’s not exactly a glamorous topic, but many people experience it: a sudden, sharp bolt of pain in the backside, sometimes nicknamed “lightning bum.” The sensation can be intense enough to stop you in your tracks—yet it may disappear just as quickly, leaving you wondering what on earth happened.

The term generally describes a sudden, electric or stabbing pain in or around the rectum. Episodes lasting only seconds can sometimes be related to brief spasms of the anal sphincter or pelvic-floor muscles, including a condition called proctalgia fugax. It’s different from “lightning crotch,” a term commonly used for shooting pelvic or vaginal pain, particularly during pregnancy. Occasional brief rectal pain may not indicate anything dangerous. However, when these painful episodes keep returning, become more severe, or appear alongside other symptoms, there are several possible causes worth knowing about.