A joke or pun that is so painfully unfunny, it can only be said by a person named Jay.
For a joke to qualify as a Jay Joke, the reaction from the audience must be either:
a) Everyone immediately stares at the person who made the joke with a look of sheer disappointment
b) Everyone laughs because of how terribly unfunny the joke was (not out of respect)
c) Someone immediately changes the subject to pretend like the Jay joke was never said
Me: Did they name Hearthstone Pizza after the game called Hearthstone?
Jay: H-hey d-dude... CS:GO Pizza Hut
Me: *Tilts head down in shame and whispers under breath* What a fucking Jay Joke