Dunno if I buy your take on this. The fans of teams that play USC in the PAC-10 are known for jingling their keys as a dig on USC’s student’s reputation as a bunch of rich kids (mocking them for having expensive cars- doesn’t make much sense to me, but whatever).
I can see this coming out of that practice.
See this thread.
http://www.democraticunderground.com/discuss/duboard.php?az=view_all&address=132x6666480
The idea originated at KOS as a way to rattle Sen. McCAin because of his owning 7 houses. DU picked up on it and it got twisted to use it against McCain to remind him of prison guard keys. POW bad memories.
I think the point here is that what started as a taunt on his 7 houses has morphed into the prison guard imitation.
It’s common practice during kick-offs in Big Ten games.