Well clearly "function" is "better", because it's less prone to typos, easier to read, and makes more sense. But if you can make a good argument to go with "fun

Well clearly "function" is "better", because it's less prone to typos, easier to read, and makes more sense. But if you can make a good argument to go with "functioooooooooooooooooooooooooooon" then go for it.