I still do. Something I started doing in the back of classes in high school (15-17) when my dick was driving me crazy. I had to be careful to unzip my pants, take out my erection, pushing back my pubic and shaft hair so it wouldn't get pulled when I rolled my reservoir-tip condom down to the base before going all the way with my right hand, filling that condom. Had to be careful my facial and body movements didn't give me away. One time though, a male teacher got up unexpectedly, and was by my side right when I was in the middle of a full body orgasm. I think my face gave me away. I was afraid he'd write or call my parents, but he didn't. He watched me take it off, tying it at the top, then wiping my penis before walking away. I think he saw me throwing it in the waste basket near his desk.