I spent a couple of months last year studying bluegrass in North Carolina, and I learned that there are is one tune you never ask a banjo player to play for you. Foggy Mountain Breakdown, Earl Scruggs’s most famous instrumental, is a tune so familiar, so oft-played, that even suggesting it at a jam will mark you out as an idiot know-nothing newcomer. It’s the equivalent of self-identifying as a Trekkie, when the correct term is Trekker.