That cheer was started by Navy about 10 years ago. Apparently, some of their lacrosse players began doing the cheer at the end of football games and it caught on with the Midshipmen/student section. Now, it has become a tradition. When they are running out the clock in the final 2 minutes, you'll hear a single Midshipman yell, "I!" And the other 4,000 Midshipman respond. It's pretty cool to see. The Washington Post sports columnist, Thomas Boswell, wrote a column about the cheer and its origin before the Army-Navy game around 2003 or 2004. (I'm too lazy to find it and link it though..)