If you missed Punch Brothers on The Tonight Show last night, here is the video from the June 16 episode.
The song is Rye Whiskey, from their newly-released CD, Antifogmatic. Listening to the lyric, it would seem that the brothers are largely in favor of the distillation in question.
The video below is for the entire program, but it is broken into chapters. Once you click the start button, you can click on the final chapter marker and go straight to Punch Brothers.
Looks like the studio audience liked them just fine.