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1.
To jack-off while defecating.

Usually done by Fat FFXI nerds who dont have time to complete each task seperately because they are too busy engaging in online parties and lvling up their ultra-uber Black mage.
"Jim is such a dirt-bag who Crapsterbates all the time"
"I was thinking of your mom while i crapsterbated"
by JdeL March 17, 2005