Once when I was riding through Harlem in NYC, a teenager (maybe only 12-14) threw a rock/stone at me, and hit me hard. That's what I mean.
I had this happen to me while riding the Seagull Century. Some kid (probably 8yo) and his friends all pelted me with rocks. I saw the rock travel from the hand one one kid all the way until it struck me in the leg. He took off running back inside his apartment after I yelled at him. If I wasn't on the ride, I'd have followed the kid back to his place to complain to his parents.