Snowball fights: What rules, if any, should be observed?

Still thick of snow here in england town & a good excuse for lobbing snowballs at like minded folks. The more the merrier as far as i’m concerned, a right battle royale involving hoardes of game participants, fantastic fun.
There are certain “rules” to follow though, at least for me & they are as follows…

Never pick up yellow snow
Only throw at those prepared to play
Don’t toss at passing traffic
If someone gets hurt, particularly a child, see that they’re okay.

Other than that i’m good to go, so how about you?
If you see no reason to indulge in the pleasures of a good natured snowball fight then that’s fine, but don’t be blowing wind all over this thread, move on or you may get hit in the eye!!