An informal noun. A mouth that behaves like an anus. Used to describe a woman's (or man's) mouth whose fellatio feels like anal copulation. All negative connotations to the anus may be attached, such as: fecal matter, foul odor, homosexuality, etc...
Yo, that bitch had an assthroat; that shit felt good. - The only assthroat here is you, nigga; your story is straight-up bullshit.
by "Dan" the Man July 08, 2010