Masturbation restricted to the ass region. Usually performed by placing dildos, buttplugs, fingers, toothbrushes, or whatever else may be handy into the anal cavity. Lube is optional but highly recommended.
Suzy had never considered assturbation until she overheard Julie talking to Maria about shoving a 9 inch vibrator up her ass while fantasizing about Tom (Suzys dad).
by mindrape November 15, 2005
Masturbation focused on pleasuring the butt, whether it be by massage or insertion.
Wow, this banana is frozen rock solid. I'm gonna have a good assturbation session tonight!
by Twiggins Q. Neugebauer June 20, 2011