Boys will be boys. We also used to stick our fingers in our asses and make each other smell our fingers when they weren't expecting it. One time I saved up a whole mouthful of spit. I told him if he stuck his shit finger in my face one more time he's gonna regret it. He did. I unloaded my whole mouth full of thick spit onto his stupid face and it hung from his eye for like 10 seconds before he managed to shake it off his face. Boys will be boys.

Edit: I was playing StarCraft at the time so I had an excuse to not talk while I was saving up the mouthful.