Sharmeka Moffitt told an implausible story: she was set on fire by three strangers who wrote "KKK" on her car. Social Justice Warrior sites like Racialicious reported it without reservation.
It turns out Moffitt lied.
To be fair to the SJWs, in my younger days, when racial issues were much tenser than today, I believed Tawana Brawley's story of being raped by white cops. When that turned out to be a hoax, I realized I'd been both racist and sexist in assuming a black woman would not lie about something that horrible. Now I try harder to reserve judgment until a claim has been investigated.
If you google "hate crime hoaxes", you'll find that just as racists often say people of other races attacked them, social justice warriors often say racists and sexists attacked them. People who think they're supporting truth in the war against evil love to lie about the people they consider their enemies.
Possibly of interest: Nebraska Woman Charlie Rogers Faked Anti-Gay Hate Crime, Police Say - ABC News
ETA: Hate crime hoaxes present burdens, lessons for college campuses | Inside Higher Ed