An offensive insult used to describe a female that like prefers underweight males, indirectly referencing their intercourse which would resemble a pencil being sharpened.
I saw her in the car with that skeleton-looking kid, you know she's being used as a human pencil sharpener.
A euphemism for messy anal sex with a man with a very slim penis
'hows it feel babe, are you enjoying our experimental session'
'aye babe this is class, only problem is me shaft looks like a grease pencil'