Whenever an opposing player hits a home run it is natural to want to throw it back onto the field in disgust. But that is a Cubs tradition so that can be a problem. On the one hand you want to reject the homerun, on the other you don't want to "copy" the Cubs tradition.
I was thinking that throwing it out of the stadium would be an interesting twist. But there are a couple of wrinkles. Depending on where you are sitting, you may need the help of others to get it out of the stadium. The teamwork element makes it an even cooler idea, but I don't think stadium security would smile upon tossing a ball around in the stands... or over the wall for that matter. Setting the ball on fire, while also being very cool, would also get you tossed by security, and possibly arrested.
Any ideas? Also, this isn't restricted to opposing home run etiquette.