A fork of Rural Dictionary
Employing one's knob outside the confines of marital bliss.
Amelia: Things have not been the same between Charles & I over the last few weeks. He seems so... distant. Isabella: What do you mean? Last time I saw you both, you seemed so happy together. Amelia (staring into her tea): He isn't as... "attentive" as he used to be. I'm afraid he might be knobbing out.
An expression of genuine amazement that makes a male want to get his knob out and masturbate
"look at the jugs on that - Knob out"