I.B.M. abbr. Itty bitty meat. A small penis.
Iggy Pop shot n. To "whack off over a TV's ass because it would be a pity to waste it".
Imperial barge n. A particularly majestic skin boat. "You should have seen how Mrs. Eisenhower's eyes lit up when my 9-inch Imperialbarge heaved into view." (from The Memoirs of Winston Churchill').
Irish shave n. A dump.
Irish toothache n. An erection; bone. As in: "Is that a gun in your pocket, or have you just got Irish toothache?"
I say! Interj. Expression of joy upon seeing an attractive woman. Attr. Terry Thomas.
I.R.S. abbr. Itchy Ring Syndrome. Irritating anal affliction caused by insufficient wiping of the chocolate starfish (qv), or inflammation of the farmers (qv).