One strategy we might be able to take is to use all their terms as soon as new ones pop up. Anti-racist? Yes, we're anti-racist. When you post something on social media that's actually anti-racist, don't describe it as anything other than anti-racist. It's not "anti-anti-racist", it's anti-racist.

This will muddy the waters and reduce the impact of those terms.

Anti-fascist? Yes, we're anti-fascist. We're not anti-anti-fascist.

When talking about black on black crime? #BlackLivesMatter

Confuse their speech. Reduce the effectiveness of their slogans.