For sheer inanity, it's hard to beat "Found a peanut, found a peanut, found a peanut last night ..." sung to the tune of "Clementine". Very popular among nine-year-olds circa 1963, when I was nine years old myself. Or perhaps "Hey bus driver, speed up a little bit, speed up a little bit, speed up a little bit. Hey bus driver, speed up a little bit, I wanna get home some day" -- not to speak of a whole whack more of really traditional genuine folk songs that little kids just *love*.

Big Blue Frog wasn't a folk song, but it sure had -- and still has -- all the qualities of a seriously good novelty song. "It's not as bad as it appears, he's got glasses and a PhD!" I loved it when I was 14, and I still do.

As for "Don't worry, be happy", it's less a song than a genius arrangement of melodious sounds all generated by Bobby McFerrin, a seriously under-rated musician.