Guest Pagan - you're wrong. It's not 'I'm gonna f--- you up' at all. Neither is it Creole. It's a Choctaw, Houma and Chickasaw greeting meaning 'It's very good'.
If you want to know the real words and their English meaning, on Google type 'Iko Iko' in the searchbox, then click on 'Iko Iko Wikipedia'.
You'll see the words are not at all as they're sung - there was no Jocomo, it was no one's name. Jocomo is how Sugar Boy Crawford phonetically copied down the Indian chant he heard between two tribes at Mardi Gras in New Orleans in 1953. He copied down 'Jocomo fee no' when they were really chanting 'Chokma Fina' which means 'It's very good'.
I know Dr John and others have given their own opinions on what the words mean (Dr John actually said it meant 'eat your pants') but seriously, Dr John isn't exactly a linguist. He can't speak a word of French Louisiana Creole, and the chant is entirely in Creole except for the one Indian phrase Chokma finha'.
If you don't feel like reading the rather long Wikipedia article, wait till next week, when you'll see a Youtube video which makes everything very clear.
Ian Cully (Yanne)