Most confusingly, in Finnish (and German, I've been told), "hai" means "shark". This word apparently comes from Swedish word "haj".

Gypsies (at least according to linguistic stereotype, I don't know that much about actual usage) use it as a greeting in here. Indeed, this is how "hi!" sounds like, right?

(A really, really, really old and stupid joke that even the Pharaohs thought was ancient involves a scared Finnish swimmer quickly swimming for the beach and a gypsy who was swimming with him...)