Mine comes from how I spent many, many times out during Illini basketball and football games during my five year Illinois career (81-86).
I was in the Marching Illini and the Basketball band. During Basketball games, my fellow Baritone Sax player and I were so involved in the games, we often neglected to play during some of the time out songs we were performing...most often...the William Tell Overture, which rolled right into the Blue Brothers riff. We routinely got the stink eye from the director because of this, so we decided to do a poor imitation of the Blues Brother dance for the song from the movie ... complete with an awful cartwheel. We originally just did it at women's games, and for our own (the band's entertainment) ... but we were approached by one of the Associate ADs (and some spectators) asking us to do it at Men's games.
We walked out to center court during a nationally televised Iowa game and did the dance once. ONCE. Turned out THAT violated some B1G rule. Oops. We kept it to the sideline after that.
Got pats on the back and 'that's pretty cool' comments about it from Heathecoat, Keady and, even, Knight. After the last one, I asked him why he was watching the band screw around during a timeout, shouldn't he have been yelling at his players? He just laughed, shook his head and muttered something about "F'ing Illinois."
My partner changed after a couple years due to graduation, and I saw other subsequent band geeks doing it for several years afterward. The dance changed along the way, but the spirit remained.
It was a fun part of an even more fun experience with the bands and figured I'd bring it along as my moniker here. Not that I post very often...