You not only knew MG, but why MG was MG.
You can sing the blues in Scots Gaelic.
You can name the members of the Layabouts At Large.
You own the complete Blue Plate Special AND the Blue Bottle Special.
You know what is meant by "perfect pitch."
You can discuss, at length, uillean, piobrach, small, Northumberian and other pipes but refrain from doing so out of consideration for others.
You realize, deep down in your very soul, that the trumpet is superior to all other instruments in existence.