We used to toss water balloons at moving cars, etc...
One time in the back of the bus (6th grade or so), I tossed a pear out the window at a mail truck running parallel to us. It smashed his windshield. He was none too pleased, he managed to get the bus pulled over and yelled at everyone to fess up, but nobody ratted me out 😀.
When I was maybe 9, my friend and I walked to the local ice cream shop and got Slurpees. I got a giant one, and then decided I didn't want all of it. So I set it at the top of the stairs, which overlooked a little eating area where you could sit and enjoy your ice cream. There was a guy down there with a couple kids eating. I ran up to my 2/3 full giant Slurpee and booted the hell out of it. It sailed in a perfect arc and nailed the guy right in the face, and slurpee splattered all over him and the kids, and one old guy sitting at another table. Direct hit. So we just started running - I don't think I ran that fast in my life before or since. Got away clean.
We used to toss eggs at EVERYTHING - we were about 15-16 at this point. We'd go around egging everyone and anyone. Once, on a hot summer day, we egged a truck w/open windows and a lawnmower trailer attached to it. Probably 6 made it in the windows and splattered on everything, and a number were outside. A bit down the road, we saw the crew whose truck it was trudging back to it all tired and sweaty with weedeaters. Obviously had just finished the job. We waved at them. I still feel really bad about that one 🙁.
We used to have Roman Candle wars when I was about 10 or so....those were a great time, until one kid caught fire and had a couple small burns before someone put him out :Q. The funny thing was, we were in the middle of nowhere, with no liquid of any sort...plus the fire was getting pretty large. So my buddy peed on him to extinguish the blaze 😀. We were laughing so hard we couldn't walk for 15 minutes. It was even funnier cause the kid really had to go, plus he didn't like the guy on fire too much, so he "accidentally" got his face and hair too, lol. He was soaked!
One time I remember a buddy of mine went on vacation. They only had one car, and left it in their single car garage when they went on their trip. It was a Civic hatchback, so not very heavy. In the middle of the night, a bunch of us snuck into the garage through the side door, lifted up the Civic, and turned it sideways in the garage. There was maybe a foot of clearance on each side 😀. I was lucky enough to be around when they got back from their trip - me and some friends were hanging out at my friend's place across the street. The look on all their faces was priceless 😀. I still don't know how they got it out.
Oh, and once we put a solid propellant model rocket engine (one of the giant ones) in someone's mailbox, and set it off. It was one of those nice mailboxes too, with a wood frame and everything. After we lit it, it got really violent in there, so we kind of spooked and ran away. Came back a half hour later and the whole thing was burned to the ground :Q.
There's a bunch more, but those are the best that I can remember at the moment.