Mud fights were a regular thing at the lake we went to every Summer, Pilling's Lake.  Sometimes they would be melees involving gangs of kids but just as often they were one on one.   The combatants would go out in water from waist to neck deep.  You'd have to dive underwater to get your ammo.  Throwing any kind of mud you could come up with was allowed... even the black, greasy stuff.  Throwing mud with pebbles in it was akin to using nerve gas in a real war.  You would be ostracized or worse.  Just splattering your opponent with stinging mud was bad enough but that wasn't the quietus.  The real art of this type of battle was to time your throw so that when your opponent came up gasping for air after gathering his mud ammo he would open his mouth to a big gulp of mud instead.  Then he/she would choke, gag, and possibly cry.  What fun! As I said, this was a very regular thing in my childhood.  Small children to teenagers partook.
    So what sort of idiot things did you do as a kid? 

   In the mid sixties there was a commercial that was very popular.  The Ajax White Knight. https://www.youtube.com/watch?v=Wrqf8mODVzQ
We kids thought he was cool so we got long poles from the woods and would literally joust on our bicycles.  We'd charge each other with our long lances chanting "stronger than dirt, stronger than dirt!"  It's a miracle no one was seriously injured.  A neighbor lady thought we were going to kill each other and called the cops on us, putting an end to our jousting.