FLeshlights are currently the most common masturbation aid for men.
They are canisters holding a solid gel, usually in the shape of a vagina. There is room in the fleshlight for a man to stick his erect penis through the vagina-shaped rubber, and experience a feeling very similar to actually having vaginal intercourse. There are very famous porn stars that have let the makers of fleshlights mold their own vaginas, and provide men all over the world a chance to see what is really is like to have sex with them. Fleshlights are a relatively new product, but millions have already been sold. There is (believe it or not) an actual patent on the fleshlight. I would have loved to be the patent examiner for that one!