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1.
The act of masturbation while excreting feces so that as the semen is emitted from the penis in an orgasm a poo is shot out of the anus at the same time, creating intense euphoria.
Ohh man I had the best poo masty 10 mins ago, there is semen on the floor
by RORYKNIGHT August 21, 2008
 
2.
1, To finger ones ass while masturbating 2, To defecate in ones hand, and then use that hand to masturbate
Damn, i heard that Michael loves to get into the poo masties after listening to Elton John
by jigsaw666 April 08, 2008