He was hilarious in his first appearence, as another character, before he became a regular.
MASH – 3×01 – The General Flipped At Dawn, immortalizing these words:
Now, feel at ease. Just tell in your own words… But first, a number. You know, a musical number, you’ve got it in your blood, boy. Just let it out.
“Hey, hey, Uncle Fud It’s a treat to beat your feet on the Mississippi mud, It’s a treat to beat your feet on the Mississippi mud.”