The small flap of skin in the anus that causes the fart sound when air is passed over it. If for what ever reason the lettuce is stuck to one side or another, it may cause a high pitched whistling sound. Most everyone has ass lettuce unless there is undue trauma caused to the anal cavity from homosexual activity, or hetrosexual anal fornication. Which will in turn cause most of your farts to sound like a hollow wind through a cave sound.
Jim talked to his plastic surgeon about anal rejuvenation. After the football team ran a train on him his ass lettuce was completely obliterated.

Mike gently leaned to his right side during his english test hoping to silently pass gas. Unbeknownst to him the mexican food had left a sticky film on his ass lettuce causing it to whistle a high pitched tune.
by Mikehoncho November 12, 2013
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