Lyric discussion by Nusquik 

Cover art for Knee Socks lyrics by Arctic Monkeys

I don't get this part: "In late afternoon, the ghost in your room That you always thought didn't approve of you knocking boots Never stopped you letting me get hold of the sweet spot By the scruff of your knee socks"

I mean, I don't know its meaning at all... Maybe some english speaker can tell me?

Thanks!

It's basically about sex, and how someone's disapproval lingered on her mind but it didn't stop her letting him "get hold of the sweet spot". Alex is a dutty genius.

Knocking boots is a slang for sex.

Scruff is just getting hold of something at the top, like how you might pick a kitten up by the 'scruff' of the neck.

"Knocking boots" is also a slang term for sex