An Egg-Citing Story is an episode from the fourth season of Garfield and Friends.
Orson tells the story of when Sheldon was born.
After working on the tractor, Orson decides to bathe in his waller, but the mud has been removed in place of the cast's fan mail. One letter in particular asks about Sheldon. Orson decides to tell the story of how he came to be.
Back when the two of them were still eggs, their mother abandoned them, so Orson took over. He sat on them for a long time until they hatched. Eventually they did. But one of them decided to stay in the egg due to knowing what the world would be like.
Of course, being an egg wasn't perfect for Sheldon. Some of the other chicks didn't want to play with him because of how he looked. So he left. But the weasel was about the farmyard and kidnapped the other chicks, leaving Sheldon to save them from him. This caused the chicks to show more respect to Sheldon and never make fun of him again.
And so, that was Sheldon's origin story. Orson decides to head back to the tractor to finish fixing it, but he then finds out that Roy and Wade put his mud in the tool shed.