Shitcum is what one does when in a state of extreme anger or rage; to shitcum in ones mouth is the ultimate act of disrespect. To do it requires a large will and steadfast self-discipline. The shit must be followed by the cum after no more that 3 seconds. While shitcum is normally placed in the mouth, it can be deployed anywhere on the body.
Sal had to evacuate his feces, and wound up taking a shidump, which resulted in an extensive, overdrawn session of lurid defecation, thus alleviating his ardent anus.
"Ah man, don't go into the restroom, I just took one big shidump!"
"That shidump made all the difference! I feel lighter now."
"Alright let's eat, but first let me take that shidump I've been waiting for."