So the Guardian has a photo album of Olympians and their tattoos. The first one up shows our guy Phelps, and you can see on his hip bones the Olympic rings and a block M. Their caption:
"Michael Phelps has two tattoos peeking out of his trunks - one of the Olympic rings, the other an M for his home state, Maryland."
Now, I am unfamiliar with British loyalty tattoos, but is it common practice to just put the first letter of your city/region as an emblem? I mean, are there guys with L's on their shoulder blades for Liverpool? N's for Northumberland?