I remember the multiple penalties for being too loud, followed by the PA announcer pleading with everyone to quiet down. That's when everyone got out their keys.
A few other memories of that game:
Many people came prepared with yellow blankets, scarves, etc., to wave when penalties were called.
Vai Sikahema returning kickoffs without any shoes.
Lots of signs asking "Who's Bryant Gumbell?" or other references to Gumbell's "Bo Diddley Tech" remarks earlier in the year about BYU.
Just being so excited to be in the stadium and see the players I had come to idolize from watching via the satellite dish at Grandpa's house.
Being so proud that we were the reigning National Champions of college football!