Back in the groovy '60s and '70s, dildos were often made of materials that could be a bit, well, irritating or rubber that couldn't quite stand the heat of passion. But then, Gosnell Duncan, a guy on a mission to find a solution for his erection woes, reached out to General Electric, who happened to be dabbling in silicone at the time. They spent nine steamy months perfecting a formula safe for human insertion.