Maybe this sounds dumb, but perhaps if the announcer guy announced at the
beginning of the game that throwing objects out onto the ice can endanger
the safety of the players people wouldn't throw stuff on the ice.
 
I was really bummed when I saw people flinging those little pre-wrapped
slices of american cheese out onto the ice after the Gophers beat the
Badgers -- apparently it was a way of making fun of the Wisconsin
"cheeseheads."