I looked it up and the first result was a slogan for a guy running for mayor in 1923

I'll assume you're legitimately asking..

At a nascar event the crowd started a 'f**x you biden' chant and the news covering the event (and hearing the chant) tried to hide it having an interview with a driver called Brandon, and then claiming the crowd was chanting 'lets go Brandon'

Pretty much highlights how the MSM works these days + social media can't ban you for it, thus 'lets go Brandon' became popular

Why not just say it then?

Also hate to ask but what is msm. "Methylsulfonylmethane is an organosulfur compound with the formula (CH₃)₂SO₂. It is also known by several other names including methyl sulfone and dimethyl sulfone. This colorless solid features the sulfonyl functional group and is the simplest of the sulfones". First search result.