Most professional musicians who make it to the world stage are rather beautiful. It's part of the deal that they're more attractive or interesting in the face than most.
But no matter how gorgeous that mug, if they're putting even smidgen of soul into their efforts, their face is gonna show it. They often look as though they're having a rough time in the John after an unfortunate encounter with street meat or as if in the throes of true ecstasy (which feels better than it looks).
Though some might see it as a translation of "spirit" or "passion," these funny "O" faces offer the rest of us ugly fucks the chance to humanize celebrities. It just so happens that the following lookers display hysterical shred-face when wilin' out. This collection of grimaces lays out pretty much the worst best of them.
See also: Ultra 2014's 25 Best Bass Faces