1) The condition of needing to relieve oneself through bowel movement. Having to take a shit.
2) In card games, hanging on to a '2' card, esp. Uno or Gin Rummy - it is a defensive strategy of game play to have only one remaining card of low value, or as in the case of Gnagno (Friulian card game), it is an offensive strategy to harbor it for late use in order to force a player to draw two unwanted cards.
3) The first album to be released by Fez Wrecker's Junkyard Jug Band in early 2013.
1) "Dude are you okay? You seem a bit fidgety."
"The toilet is occupied, and I'm harboring a deuce!"
2) "What the fuck, you were harboring the double deuce?! That's four points for me!"
3) Have you heard that new shit from Fez Wrecker's Junkyard Jug Band called "Harboring a Deuce"? It's not as crappy as you'd expect from those constipated cats.
Straining on the toilet to release an over-sized piece of crap causing you to exclaim "wraaaaaauuuugh" (meaning "Mommmmy!" in Kashykk-speak); when the offending fecal matter is finally released and inspected before flushing, it is covered in ripped out butt-hairs.
From the WC: "Wraaaaaauuuuuugh!!!!"
Joe: "Hey, is that Bob in there?"
Betsy: "Oh, yeah, sounds like he is Harboring a Wookie again...maybe he needs a laxative?"