The cure for masturbation
Some people get sexual pleasure by inserting objects into the urethra (the tube through which urine and, in men, semen, flows).  . Other objects such as ball point pens and thermometers are sometimes used, although this practice can lead to injury and/or infection.  Some people masturbate by using machines that simulate intercourse.
Also check out this great Vice article, 'Death Grip Syndrome': Internet Myth or Penis Ruiner? , featuring perspectives and commentary from real sexual health professionals.