Testis cancer is the most common malignancy in men between the ages of 20-40. A monthly exam can identify a tumor when it is confined to the testicle and is nearly 100% curable. Check out this very entertaining video and make it a point to perform a monthly testicle self exam.
http://www.kevinmd.com/blog/2010/11/testicular-exam-sung-michael-jackson.html
Dr. Neil Baum's Urology Blog 