You already know what this is...it's when you're trying to take a massive dump and the turd bomb reaches the sphincter only to release tiny little bomblets. They usually are responsible for that machine gun poop that splashes your ass. It feels like you're pooping Raisnettes.
Mikey: Man, I must've flown over Hiroshima in my previous life.
Mo: Why would you say that?
Mikey: Cos I just killed the camode with my butt cluster bomblets!