An Oreo (Black on the outside, White on the inside) is a Black person who intentionally and sometimes unintentionally (raised around a lot of Whites with no Black connection) takes up the societal norms/custom and values of the White American population and disregards with intent/non-intent Black societal norms, customs or values.
Using Standard American English, not wearing the latest garbs from popular hip-hop/street clothing lines/artists is not an indication of this, however you will have some Blacks that are intimidated and/or insecure about who they are as Black people and will incorrectly use this term as a defense mechanism because they are intimidated.
When you show that your "deviation" so to speak isn't real deviation and that you can still connect and relate to the experiences that Blacks face and can understand the use of common wording or phraseology used in many Black communities, regardless of acculturation, without criticism you will not be considered an Oreo.
Learn to code-switch (Ebonics is our native tongue so to speak) or just be down to earth and relatable and proud of being Black and you won't be considered an Oreo.
Black people, stop calling other Blacks Oreos because you're intimidated. Many of them are not true Oreos. Many just don't know who they are and don't know their history.
Real Oreos do exist. They are called sell-outs, these are folks who will disregard any and every cultural element of Black culture and cling to the norms/values and beliefs common in White communities & about Blacks; they will do all they can to remove themselves from being associated with Black people and will openly criticize and side with any and every negative idea about Blacks and will renounce any ties to Black cultural elements and especially those that are humiliated/degraded in mainstream America and they will ONLY date, marry and socialize with people of a different race than them; they will not attend Black events, support Black causes etc...
Tracee Ellis Ross is a great example of someone who is not from the hood, but is NOT an Oreo; she speaks what's considered "proper" english and is proud of her Black ancestry. Rhonda Ross too, speaks "proper" but is proud to be Black, likes nice things etc, not an oreo.
Diana Ross is a great example of someone from the hood, who speaks "proper" english, but I've heard her use some phraseology and words specific to the Black community; it's embedded. She's a great example of someone who keeps it real, is proud to be Black, likes nice clothing/homes etc... but isn't detached from who she is and where she's come from.
MJ, yep believe it or not, he was proud
Brian J. White & Tiger Woods
I hope this explained what a true Oreo looks like and what it truly is.