Jason the Bird is a classic character appearing in many different universes and contexts. He originated as an Angry Bird character named "The Epic Win".
In Stale Pancakes 9, he shares Rob Erase's birthday with the rest of the cast shortly before being killed by an evil tree.
In a brief scene in Jeff and Jeff, he is seen sitting at a desk behind Nerd Jeff in the Jeffs' classroom.
Jason's so cool, man.
The epic win is an Angry Bird I made up.