2.) An command insult implying that the subject of your verbal abuse should "shit a dick" "dick" in this case meaning a log of feces, and perhads tear thier anus in the process.
3.) When used casually shit a dick siginfies dissappointment in a given situation.
4.) Shit a dick can also be used to reference episode #1102 of South Park: "More Crap", where an enourmous turd starts a chain of events that leads to the unraveling of a massive conspiracy.
2.) "God damnit Burnice, why dont you go shit a dick and die!"
3.) "Aw shit a dick, i dropped my ice cream.. fuck"
4.) "HAAAAAAAAAAAAAAAAAOOOOOOOOOOOOOWWWWWWWWW! hot hot hot hot hot, hot hot hot hot hot, OOOOOOOOO AHHHHHHHH!!!! ahhh..."
Also could be used to insult someone by saying they are gay, implying that they, a guy, had anal sex with a dude.