Whatsit
From Homestar Runner Wiki
File:whatsit poop.PNG
A pile of vile whatsit
Whatsit is a polite term for what The Poopsmith shovels.
Homestar gets some to fill his arbitrarily self-imposed weight requirement of "like a million pounds of candy". The Poopsmith serves up a dish of it to The King of Town for no sufficiently well understood reason in the newer Homestar Theme Song video, which nearly makes the KOT lose his lunch.
First seen in The King of Town DVD, it shows up whenever The Poopsmith is "on the job".