"Oy" and "vey" are two very old Jewish interjections which both mean "woe." Oy is found many times in the Bible (See Numbers 21:29, I Samuel 4:7, and Isaiah 3:11 for a few examples). Vey is newer than oy; it is oy's Aramaic equivalent.
Today, oy and vey are often used together. Oy vey is the ethnically Jewish way to react when you find out how much your son's root canal will cost, or when you find out that there is a two hour wait time for a table at the restaurant at which you just arrived.
Sometimes you'll hear people groan "oy vavoy," which is Hebrew for oy vey.1 Those who prefer Yiddish lamentations will often cry "vey iz mir" which means "woe is to me."
Let's pray that G‑d sends us Moshiach already, so we can stop waxing eloquent about our woes and expand our vocabulary of positive interjections!