A huge crap after eating a large meal.
"Man I just ate a 3 brats and and 2 pieces of cake."
"Yeah your going to take a shitosaurus tomorrow"
A troll making themselves seem big and tough when it is obvious they are lying because they have no life.
Shitosaurus: dude i swear im the lead quarterback at my schools football team and we are so good but im the best player and everyone on the team likes me. like every girl at my school wants to go out with me too. i swear i on my life.
Person being Shitosaur'd: Oh god, not a shitosaurus! I hate these people...