This is the female equivalent of stealing somebody's girl, but instead of stealing yo man, the person who attempts to "Steal Yo Nigga" in this situation does something that specifically appeals to a black person. This is a famous line from the Tiktoker 9Trevv.
9Trevv: Cooking with a nigga! I'm cooking chicken friedwatermelon, and some fresh cornbread that yo niggas are surely gonna love! I bet my food can steal yo nigga!
This phrase originated from, was popularized in, and was entered into prominence by Chappelle's Show in episode #204 where Rick James says "fuck yo' couch, nigga" when he is caught kicking mud all over Charlie Murphy's white couch.
The phrase entered pop culture lexicon to mean audacious indifference or apathy in acts of disobedience or to a given situation.