Something indescribable with words, only with your eyes. Your eyes aren't capable of capturing the pure mass of your mother. The absolute planet of a woman. Usually used to insult someone and hurt them mentally. No one can recover from "your mum" especially if she sat on you.
Girl: you smell bad
Boy:your mum
its a joke thats funny because of joe biden
defining something big and fat
sometimes hot
Greefy: he look at that big plane over there. I wonder whats the dimensions of it
Beefy: I am very sure thats around the size of that of your mum.
This meaning is used for someone who want it to put in your ass, people who most commonly use this term really want it in the ass, the mum part is a way of saying the you have sexual relations with someone mother.
Someone: What are we going to do
You: I'll Put it your ass, like i'll put in your mum
Someone: OMG yess baby
I'll Put it your ass, like i put in your mum
when your mum gets reviewed by the mailman
"Ding Dong"
Mailman: "Can I review your mum?"