
After I did some research for this. I found out the true reason behind it:
Most of the time, it's mainly for picking nose and the ear. It's used as a tool to remove their earwax. And many females, in the US, think the men having long pinky nails are disgusting. So if you, unfortunately, happen to be one of them, it's highly suggested that you should go to a local nail salon to remove them as soon as possible.