It's common for lower-class Chinese men to have one long nail. I tend to assume the reason isn't drugs, but I don't know what it is.

I was annoyed once when I stumbled upon an advice column named "Ask a Chinese Girl", and someone had written in asking what that one long nail was about, and the official answer was "What? That sounds dirty, it's definitely not something Chinese people would do."

You can easily observe that they do do it by walking around outside. So weak support, I guess, for the drugs theory, but I still tend to suspect it's a cultural thing.

Anyone know?

I had thought it was a historically recurring status symbol, showing that the owner of the hands wasn't required to use them for manual labor.

Surely it's to show the user does not lift a single finger for themselves. Not just labour, but all useful action is shown to be eschewed by someone with lengthy pieces of plastic glued to each fingernail.

These are people who definitely are required to do manual labor.