The occasion was a commercial shoot. It's what the 1985 Bears do best these days: Evocation for Dollars.
Boost Mobile brought back a few memorable soloists/cowbell players to recreate the famous "Shuffle" video for a Super Bowl commercial. The 30-second parody will air during the first quarter. Despite the video's popularity, the Bears have never remade it, for various reasons. And that's part of the joke in the commercial.