What is Knob Polishing?
1.
continued stimulation of the head of the penis after ejaculation, when it's become uncomfortable, usually accompanied by verbal taunting and usually while the male's hands are tied out of the way.
I polished his knob until he was crying.
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2.
To get your dick sucked.
Person: Interested?
Me: In a knob polishing?
Me: Why certainly!
See