I hadn't actually heard of it either, from one of the first results:

> This whole thing got started earlier this month, at the Talladega Superspeedway. Brandon Brown had just won a NASCAR race. And sportscaster Kelli Stavast at one point commented during an interview with Brown afterward how the crowd seemed to be chanting in his honor: ‘Let’s go, Brandon!”

>Unfortunately, that’s not actually what they were chanting. Not even close. The crowd was very clearly addressing President Biden, not Brandon. Only, with an f-bomb in front of his name instead of “Let’s go!”

Video: https://youtu.be/kQ8asiDn2_A

Source: https://bgr.com/politics/lets-go-brandon-the-backstory-of-th...