Giving a large shot of a hard alcoholic beverage to someone by way of their butt hole while they are supported upside down. This is favourable because alcohol entering the anus is absorbed into the bloodstream faster then if consumed orally. Try it with friends!
doctor: "this is aroutine procedure"
patient: "then why does my ass hurt so bad?"
doctor: "this is known as a flesh enima, you'll have some swelling for a few days"
During a barium enima procedure the patient can no longer hold the barium within theirselves and it explodes out of their anus and covers the xray technician in a wonderful surprise