When a male submits his penis for
oral sex (fellatio). "Knob" is a slang word or euphemism for head of the penis (glans); "get polished" (polished) implies agitation or rubbing, in this case full sexual excitation of the dick head.
When the male's penis head is swollen or engorged by
oral sex, he has had his knob polished. In actuality, though, "get my knob polished" has come to mean "get a blow job" with the hope of
orgasm included.
The term is not to be confused with "dip my wick," another penile reference that usually implies penile-vaginal or even penile-anal sex.
A person who does not orally polish the knob but instead leaves it messy with saliva and/or pre-ejaculate is a knob
slob.
1. --"I want to get my knob polished soooo
bad!"
--"Don't look at me, bro. Find your own head."
2. --"I like to polish his knob 'til it's
real shiny and red!" - one of the "two gay guys from Jersey" (Fred Armisen, Bill Haider) on TV show Saturday
Night Live.