This happened to me once in my early twenties, and not by my request. The guy, let's call him Peter North, was about five feet away from my face. He had a little premature ejaculation problem, so he was taking a break. I just brushed him with my foot, and then, bam, bullseye! It stung like a motherfucker, and my eye was so red it looked like a peeled grape tomato for six hours.