The sound comes from a widely shared interview moment where Vin Diesel keeps praising a reporter, repeating it's so good with unusual earnestness. The short exchange was clipped and reposted on YouTube, then trimmed further for soundboards and short form video. Its humour comes from the contrast between his tough action star image and the soft, delighted way he delivers the line. That contrast helped it spread as a standalone reaction, separate from the full interview, and it is now used whenever creators need over the top approval in under two seconds.