Armaflex Simulator

Get a 6-foot length of 1 3/8" inside-diameter x 1/2" wall Armaflex pipe insulation at a plumbing-supply store or home-improvement warehouse (costs about $6). It's a single piece of neoprene foam rubber, not the slitted foam-plastic type others have suggested here. Cut a length 3" longer than your erect penis. With sandpaper, roughen 1" of the inside at one end, apply a 2-part epoxy cement, and clamp it shut with with the other (open) end pointing up. After 12 hours remove and install around the rubber sleeve two thick rubber bands at 1" and 4" from the open end. (The rubber bands they use to tie fresh broccoli are best.) Apply a little K-Y Jelly and 3 or 4 sprays of water, insert your erection part way, and squeeze the tube to expel air. Then thrust in and out. The inward stroke emulates vaginal sex, and retracting simulates oral. This is also good wearing a condom. The sleeve will last a year with daily use. [The reader who submitted this claims it's "the best I've found in 60 years of masturbation."]