A bad friend. One who totally fails in all departments of friendship. They forget birthdays. Never pay you back. Encourage you to do the stupidest shit and then cheese it when you get busted. They sleep with your mum. Basically a shit.
Human 1. Dude i slept with your mum
Human 2. what the fuck!
Human 1. and i killed your cat on the way out. soz.
Human 2. You prick, you're such a thumbs down friend