Major plot flaw that made it unrealistic...
The sub-plot of young Dre being brutally and continuously raped by Graffiti WHILE ALSO becoming Graffiti's punk in a prison with predominant black gangs was NOT REALISTIC AT ALL, since the movie takes place in a U.S. prison, I think in New Mexico.
It is of common knowledge in U.S. prisons that blacks and hispanics gang together and DO NOT ALLOW members of other ethnic groups to sexually assault their own (But do have a tendency to "punk" members of their own race). If a black inmate was sexually assaulted by a hispanic or a white inmate, then black inmates would RIOT in retaliation looking to kill the perpetrator. Same concept would apply if a hispanic inmate was attacked by someone from out of his ethnic group. Not the same concept applies with whites, who are minorities in prison.
Studies have demonstrated that the ethnic group that is MOST vulnerable to rape in men prisons is the one conformed by whites. Young white males become preys for sexual predators in prison, and it is also a well-known fact that whites do not protect each other while incarcerated unless they are part of some sort of White Supremacist gang.
In a real-life prison, Graffiti would have never been allowed to "punk" Dre and have it made known to the entire prison.