A hebrew word for "friend who also fuck". It comes from the word Yedidim that means friend, but the letter D is changed to Z to represent the word Zain.
David : "You woulnt believe... I slept with Yael yesterday"
Michael : "What! but you're best friends! do you mean that you're going to be a couple now?!"
David : "No stupid, we're Yezizim now"