When you say " He took the D" youre basically saying you just gave another dude your junk. Not hatin on anyone, just realized its one of those insults that when you really think about it, it's inherently gay.
Super macho morons like to think they're clever about their insults sometimes. This whole idea comes from a very HURR DURR place in our society, and has been seeded into the population since very long ago. You know, when our ancestors were wandering around the desert, making sweet sweet love to their goats and daughters.
The idea is that if you anally rape a man with your penis, then you've made the other man gay. So long as you don't make eye contact it's cool. Or, in other words, people are dumb and they can't think of any clever or witty insults on the internet so they automatically resort to penis worship.