Abraham "Abe" Simpson is Homer's fatherly and commonly just referred to as grandpa on the show. Despite being a decorate war veteran with some of the most impressive stories, Grandpa is commonly regarded as a loon and his stories considering rambling by the family.
You know, you remind me of a poem I can't remember, and a song that may never have existed, and a place I'm not sure I've ever been to.Grampa
Homer: Sorry, Dad. I was afraid the dragon wouldn't cough the moon back up.
Grampa: You idiot! Dragon always coughs the moon back up.