A phrase used to describe a certain type of person. This person is usually tall and gangly and may suffer from slight mental retardation. They usually have curly hair and most would describe them as a big dumb faggot. Many of the P-sharks listen to hip-hop music and are characterized as wiggers. These types of poop sharks may have a Jheri curl. Some famous poop sharks include Jon Heder(Napoleon Dynamite), Screech(Dustin Diamond) , and Rosie O'Donnel.
Korie Mooreland is such a douche! He must have got his degree in poop sharkology.
I can't believe that faggot! he is such a Poop Shark!
A poop tube is when you put your hand in a tube like shape and put it over someone's mouth and take a big meaty shit and stuff it in their mouth with one finger.