A piece of shit that gets flattened in between the cheeks of your ass (after an early morning dump), and throughout the course of a day, it dries and becomes brittle, just like a cracker
Man I need to go home and get rid of this huge butt cracker, it's starting to itch.
It is the worse insult you could possibly say to someone.
Possiably so bad the affended person has the instant right to commit murdeur to the name caller.