Left Hand Love

Can anyone explain this new phenomenon to me? I was walking one evening an I saw a group of men that I knew. Unfortunately I was on the phone when I approached them. The phone was in my right hand so as I reached out to give them a shake/pound/dap; I was greeted with the "Come On, Man" face and they said, "No left hand love, man!" I was astonished. They didn't touch my left hand and waited for me to switch my phone into the other hand before they would dap me. I figured this was another "young people" thing that I just didn't get, cause I'm old. Then a few days later, I'm at a theater in Pittsburgh an a gentle man older than me went to greet me. I was eating a sandwich that was in my right hand so I offered him the left to shake. He turned his face up and pulled his hand back. He said, "I don't do the left hand, man." Is this new to anyone else but me? I have no idea where this comes from, but it seems to be gaining momentum. If anyone has any info on how and where this fab came from, please post it in the comments. I have a sneaking suspicion that this new trend has a homophobic undertone, but I have no proof. I hope not because if so, this would another black eye to the image and attitude of our youth; but that's just my opinion though, and who the hell am I?