The Arabian Shotgun is a sexual act during which one partner penetrates the anus of the second partner after this partner has consumed substantial amounts of laxatives.
The receiving partner then exerts excretory pressure while the penetrating partner removes his penis. The resulting pressure release creates a spray of feces in a shotgun-like blast.
Tony: What happened to you? Did you get splashed by a semi?
Edgar: No, Erma and I did a little Arabian Shotgun.