Actually, Linus is
stood up by the Great Pumpkin every
Halloween. He sits and waits while defending the Great Pumpkin's honor in the face of naysayers like his sister
Lucy, who thinks he's a gullible moron. But Linus can only take so much
pessimism: after several people have passed and told Linus in a reasonable tone that maybe - just maybe - the Great Pumpkin doesn't exist, he gets a little squirrely and starts yelling at them.
The Great Pumpkin may actually make an appearance somewhere, but never where Linus is.