3:1 Naming Ratio

A form of naming people in a group, usually siblings, where the former 3 share similar names and the latter one has a name that completely stands out. A great example would be that one show called Nicky, Ricky, Dicky, and Don (I think that was correct) from a time that I can't quite remember.

Some Farmer: Here's my boys, Larry, Garry, Barry, and Nail. I thought that it would be useful to use the 3:1 Naming Ratio.
Me: What's that last one's name again?
Some Farmer: Nail.
Me: Why Nail?
Some Farmer: Because he was born with a nail square in his forehead.
Me: How is anyone born with a nail already in their forehead?
Some Farmer: Strange things happen on a farm.