A pencil is a slang word for penis.
A pencil sharpener is a slang word for
vagina.
Pencil shavings is a slang word for cum.
e.g When a man and a
woman have sex, the man sticks his pencil into the
woman's pencil sharpener and they have sex. After a while, pencil shavings explode out of the pencil and into the pencil sharpener.