Rectal Raisin

When you're taking a shit and you have that one last poop hanging from your rectum and you have to sway your butt back and forth on the toilet seat to get it out;
i.e. that shit that you end up wiping with the toilet paper that leaves a little clump and possible smear on the tip of your finger

Sam: 'Oh, shit! This rectal raisin is actually killing me!

Crap, it got on my finger!'