a Fergasun
A Fergasun is when someone makes a thread so stupid it could make a genius cry, and then he runs away like he stole the last pizza.
A post that says, "I think time is a lie, and I'm the only one who knows." Then the poster vanishes.
A thread that starts with, "Why is the sky blue? Because the clouds are mad." Then the person leaves.
Someone says, "The internet is a trap, and I'm the only one who saw it." Then he logs out forever.