Oy vey (Yiddish: אױ װײ) or oy vey ist mir is a Yiddish phrase with the longer version literally meaning "oh woe is me". The long version is basically never said anymore and only shorter versions oy vey and oy gevalt are. Oy gevalt means the same thing. These phrases are mainly used by Ashkenazi Jews and people mocking Jews.
It was originally used as an expression of misfortune, the opposite of mazel tov ("good luck"). But it gradually changed into an expression of astonishment or excitement. For instance, a Jew seeing a half price off sale or any other type of discount on useless yet cheap items would shout, "Oy vey!" Along with excitement toward sales and bargains, the term "oy vey!" can also associate with a negative excitement such as an outrageously overpriced item.
It sometimes is still used in its original negative meaning of "oh woe is me", but only with an added phrase on there for emphasis that it's negative. For instance, "Oy vey! It's like another shoah!" is a common Jewish expression used for a minor inconvenience like stubbing one's toe. It's never used for a major inconvience. Another example is, "Oy vey! That's hate speech!"
David: Look guys there's sale at the clothing store!!!
Mordchai: David! Shame on you! Those prices in their are completely outrageous! Oy vey!!!
Ari: Yeah David, I'm with Mordechai on this one. Oy vey, indeed!
David: What a shoah!