Fun = cheerly = Gullah "shantee" (happy, cheerful.) Naaaaah, too easy.... but then again "stamp and go" means fast food.

"Cheer'ly Man": the proto-chanty?"

“The Greeks and Romans had their Celeufma or chearing fong.”[Capt. Forrest, 1779]

"Via, via, cheerly mates!” [footnote to definition of the celeusma, Lexicon Universal, Hofmanni, 1698]