"I'm My Own Grandpa" (sometimes rendered as "I'm My Own Grandpaw") is a novelty song written by Dwight Latham and Moe Jaffe, performed by Lonzo and Oscar in 1947, about a man who, through an unlikely (but legal) combination of marriages, becomes stepfather to his own stepmother — that is, tacitly dropping the "step-" modifiers, he becomes his own grandfather.