Does anybody know any funny insults in different languages that I can use on my little brother?

My little brother and I are always arguing, like any pair of siblings. I don't want to hurt his feelings or go too far, but sometimes he frustrates me to no end! What are some funny insults that I can use on him that he won't know what they mean? It would be a lot better for me to call him a dork in swahili than for me to start swearing and yelling at him :) Thanks!