I had an experience with a dreadlocked bass player wearing a stocking cap (in the summer).
He's sitting in the control room overdubbing his bass with headphones OVER his wool stocking cap, which was covering his ears as well as his thick locks.
Him: "Can you turn up the cans?"
Me: clockwise turning of headphone amp's output knob
Him: "Can you turn up the cans a little more?"
Me: more clockwise turning, looking at his face to determine if I go too far. Sudden stop to the clockwise turning. Look down - amp is all the way up. I can hear the cue mix from my position ten feet away.
Him: "Yeah, I don't know - it still sounds muffled and a little distorted."
Me: "Can you take off your hat?"
Him: Removes headphones, removes cap, pulls back hair, reseats headphones.
Him: "Holy $hit can you turn down the cans!?!"