'Sex Laws/Train On The Island' as performed by Punch Brothers
The copy I have is a Daytrotter's session from the Illinois studio's Best Songs of 2012 compilation, so I would guess I was on hunt for new music at the time.
From what I can make out, the 'Sex Laws' bit is actually a cover of a Beck song. But whatever the case, it's a thoroughly up-beat, country affair ripe with funky bluegrass slurs and enough fiddle to give Castro a run for his money. But seriously, it's pretty tight and there's some badass mandolin in there.
It was always inevitable that I was gonna liken this to Hayseed Dixie, unversed in matters of American folk as I am, but there you go.