Top definition
When two people push their assholes together and alternately shit into the others asshole, hence boomerang.

Invented by Bill Cosby in 1956.

See also ultimate dirtpipe boomerang showdown
Kevin:"What are you watching?"
Bill:"Two black trannys doing a dirtpipe boomerang."
Kevin:"Pass the KY jelly"
by TheChode April 02, 2007
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