A sexual act in which helium is pumped into the rectum of someone. Once the colon is filled with helium, the "whistler" then sucks the gas out of the sphincter, and procedes to talk in a high pitched voice.

The addition of Cajun seasonings to the asshole causes this act to be known as a "Cajun-Louisiana Train Whistle."
Suzie couldn't quite laughing after Frank gave her a rather exhilirating Louisiana Train Whistle; his high-pitched joked afterwards was even funnier.
by The Gapist March 28, 2007
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