A way of replacing the need to apologize or to say sorry, often by using this term to ease the tension of the situation. To make one seem not as responsible of his or her mistakes. my bad can also be an alternative term of equal meaning.
1: I had sex with your girlfriend last night.
2: What the hell?? What kind of friend are you???
1: Aw man, my fault! (or "my bad!")
2: Man it's cool, since you said my fault.
Something you say after you've been accused of doing something wrong, but you don't wanna get in trouble for it.
"Why everyone saying you calling me gay and stuff ,aye run ya pockets"
"My fault OG"
nahh no my fault OG imma getlil travis on you he throw them hard rocks