If you are intentionally trying to crash something in an uncontrolled manner, should you be using a plane that has the potential to hurt someone. keep in mind, these events are at fly-ins, with spectators about... not you and your best buddy flying on a sunday afternoon with no one around.
like I said before, if its a foamie with a low powered pistol... great fun, especially for the kids... .40 sized glow engine though... what would that do to a 5 year old?
There is a difference between an unintended accident and an intentional crash.... the best analogy I can think of is if you drive your car intentionally into a tree, your insurance company won't cover you if they have reason to believe you did it on purpose.. if you drive it into a tree accidentally... your covered... while the outcome is the same... the cause and intent are different and because of this your responsibility in the event is different.
we tend to think in terms of bigger faster louder... and thats the danger here....big planes with big paintball guns would definitely produce much more spectacular crashes... ( cue tim the tool man here ) but at significantly more danger to the crowd... I think thats all I'm saying.... be smart about it....