Colonoscopy? Try a barium enema! The day prior (or 2 days, can't remember) you can't eat (this really puts you in a cheery mood). Then you have to take a buttload (pun intended) of laxatives (nothing like spending an evening with the squirts every 20 minutes), then the morning of the procedure you have to give yourself a laxative suppository (a chunk of vegetable oil the size of a .50 caliber bullet) that sends you back to the crapper. Then you go to some clinic (mine happened to be staffed with beautiful young women--try hitting on some babe sometime while getting an anal probe!) for the procedure. Then they stick a big probe in the out door and inject some radioactive goo, all while strapped down to a table that's rotating every which way so this goo can drip through every inch of your large intestine. Then they fire up the camera and start injecting air into you, all while telling you, "Hold it...oh, you're doing great...I know this hurts...we're almost done..." and you feel like one of those japanese puffer fish ready to blow a major-league Chernobyl fart over Guido the anal doctor and his three lovely lady nurses.
Yes, this is disgusting...I have diverticulitus. The moral to this story: eat lots of fiber!