HBO’s deadpan darlings Flight of the Conchords have popped up in a “Behind the Scenes” video, made during a photo shoot for Maxim magazine, sporting mustaches and demonstrating their favorite “guitar faces.” Check it out, and let the PopWatch universe know your answer to this burning question: Which musician, living or dead, makes the best “guitar face”? You know what we’re talking about here, that intense performance face that makes you squirm, or perhaps swoon, but you can’t look away because you know that guitarist is feeling it! An obvious candidate is John Mayer. Who else?