behindmen Share definition Flag Usually used as a noun, behindmen is slang originating from the female hymen. Behindmen is often used as slang for when a gay male has anal sex for the first time. Joey is more bitchy than usual because he had his behindmen broken for the first time last night. behindmen by oak pwr September 23, 2010 0 0 Get merch Get the behindmen mug. Buy Now — $32.95 See more merch