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1.
Word used to describe an asshole when specifically suggesting that the person is the tube-like, shit-covered skin within the anus, rather than the air between it.
That guy just stole my seat! What an ass tube!
by Carton Jones December 16, 2008
 
2.
the lower part of the digestive track adjacent the anus; the rectum
If you have rough anal sex then you may end up with a sore asstube for a while.
by real id guy June 07, 2009
 
3.
A tube that is shoved up someone's ass. Liquids are then able to be passed through the tube into the person's anal cavity therefore giving them special sensations.
I shoved that asstube into Alby's ass and then I filled his ass with piss and rocketsauce.
by speedman225 March 16, 2007