Also See "Haunch it up". The act of expelling a very large amount of crap after having held it in for far too long.

Haunching up can take anywhere from 10 minutes to 1 hour. Prolonged periods of haunching up may lead to back problems and hemorrhoids.
Andi: Where's Kelsey? I haven't seen her for 2 hours.
.
Ralph: She's in the bathroom "haunching up". Probably gonna clog up the toilet again!
by Ralph M. Frichtl December 25, 2009
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Basically taking a dump. Use of this term though, refers to a dump that you had been holding in for a long time and finally find the opportunity to get it all out.

Coined by Ralph M. Frichtl
"Kelsey make sure nothing happens to my beer at half time, I seriously need to go HAUNCH IT UP big time!"
by AnnDee Paxton February 22, 2009
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