Yup, that is a possibility and one you want to avoid. You could start by raising the subject of masturbation. (Lots of friends talk with each other about it because by your age most of them are doing it.) If he is interested in talking you can mention that you heard some boys do it together, watching each other or trading hands. His response to that should tell you whether he is a prospect or not. If not then drop the subject and keep looking elsewhere.