The problem with all the theories is going to be the spellings, or rather the alphabets. Creole, Swahili, Yoruba &c are primarily spoken word languages. They don't have words as Mudcat would process them, just sounds. Not until any one given song or book was published anyway. But what the heck:

Iko was modern Latin-Yoruba for both an 'official' griot and the shout, yell or cheer given. Something like a town crier and “Oyez, Oyez” or “Hear Ye! Hear Ye!” in English. But... hold your mouth a little different and it could mean a sneeze or a cough nowadays. That's Creole for ya!

Giacomo & jesters: Probably nothing to do with nothing but… Italian circus performer Giacomo (Giacomino) Cireni (1884-1956,) was probably the most famous of the early 20th century. One of the first to popularize the huge, outsized clown shoes.