I was a student at Iowa State in 1972 when we played Colorado. Normal proceedure was to get to the gate of Clyde Williams Stadium around 7:30 am (this was before tailgating was popular) and drink beer and get in the stadium first to sit on the 50 yard line. The entire west side was open seating. Before the team came on the field, students would form a human tunnel for the players to run through. After they ran on the field, CU ran on the field with their buffalo. A number of students (including me) were armed with oranges and apples and started pelting the live buffalo. It went crazy, got lose and pandmonium broke out. It ran all over the field until security people, and the CU people could subdue it. We went back to our seats on the 50 to watch the game. Two years later, they did not bring the live buffalo along.