a exclaimation. A jewish term for 'oh brother' or 'what the heck'.
Neal: And then Mr. Burke assignned us a 3000 word essay on the meaning of life.
Friend: Oi Vay.
Emily's are usually annoying but you love them anyways, they have the best personality. If you don't have an emily in your life you are one lucky guy because their sheer awesomeness will tear you apart.
Dude have you met Emily
Yeah she ruined my life, but I loved every minute I spent with her