Someone who just doesn't learn from sore experience, whose knotty head speaks to repeated thumpings for trying to do something they were told not to do.
My sack-o-shit father called us all knotheads when we tried to raid the cookie jar.
(A) A person who has trouble thinking in a logical progression. this is usually caused by a profound amount of circular reasoning tying their brain into a knot.
(B) A dumb ass
That Knot Head Smerman is trying to figure out how to use the urinal again. last time he pissed his pants before he figured it out.