I attended a NASCAR race in Michigan on the weekend and stayed at a camp site at the track, partying with a bunch of drunk NASCAR fans (Many of which were Canadian as well). We piled 12 people into the back of a pickup truck, and somebody threw a half-full can of beer at the truck. A few of us on the truck threw our beer cans back at the instigator. The first 2 beer cans thrown struck the 2 girls standing on each side of the original beer thrower and one actually struck the girl in the face. An all out beer can war broke out and there were many beer cans flying through the air.
There’s something fun about throwing a beer can at someone. It’s like throwing a beer bottle at someone, without the injuries that result in beer bottle throwing. A beer bottle war would be fun, but very messy, so cans offer a nice alternative.
You might think that it’s a waste of beer, but it is American beer, so the replacement cost is minimal. Money well spent.