Who do you think of, when you here the word pencil neck?

Someone with a pencil for a neck.
Someone with a chicken for a neck.
Someone with a sunburned neck.

A geek.

That one scene in Spongebob where Plankton crawls into Spongebob's mouth and yells "hey, Pencilneck! Yes, you! Slither over here! Surrender that ice cream cone or every waking moment for you will become a swirling torrent of pain and misery!" To the guy that stole his ice cream.

A pencil

You.

Pencil neck I think of a weak guy with a small neck

Chicken neck I think of a chickens nec

Redneck I think of a blue-collar guy dressed casually living in a double wide drinking budlight in his yard tinkering with an old truck with weeds growing around it.