A brown tunnel is when a girl takes a shit then forces it into her vagina using her hands then gets a guy to plow her getting brown balls , variants include licking it out and shit swapping. The shit acts as lube for a very pleasurable experience.

Also called brown flume.
hey babe, ready for a brown tunnel? yeah i love brown balls, yummy
by browntown2 January 9, 2011
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When A guy fucks a girl in the ass and instead of cumming you pee in her butt
Dylan tryed to do a brown tunnel flood but mr. condon caught him befor he did
by Dylan Swistak February 7, 2008
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