Used when you or someone else does something stupid. It also can be used if one is annoyed, disgusted, bored, surprised, or in pain. Or just for the thrill of saying something nobody else says.
OY is a gang in Harlem particularly in Sugar Hill that is most known for their drill music. They have popular rappers like SugarHill Keem, Sugarhill Ddot, DD Osama, Edot Baby, Dudeylo, OY Quan, and more. OY has beef with the YGZ, DOA, and more. Their younger rappers started getting a lot more recognition after Notti Osama's(14yr old rapper who was one of the best in the scene) death. They started around crip descent unlike the YGz who started with blood descent.
A term used between teens of DDP (Drunk Disorderly Punks) as a way of hollering at each other and saying "hi", since they are usually wanderingthe streets and need to yell to get attention. It also serves a double purpose of letting them know the one who yelled it is one of them.
Exclamation of surprise, amazement, etc.
Most probably stems from "oei!" A West-European word, similar to the English "Oh!" or "Oh dear!" or the more modern "What the hell?!".
The written version of putting the peace sign up to your face, the "O" signifying the head, and the "y" signifying the peace sign. The Oy can be thrown up to show allegiance to one's posse, or to complement an act of mutiny upon one's friends.
Although sometimes mistaken for an acronym or as a word in itself, it should actually be pronounced as two letters, not "Oi"