Whatsit

From Homestar Runner Wiki

Whatsit is a polite term for what The Poopsmith shovels. Whatsit is also known as You-Know-What.

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 king lose his lunch. The Poopsmith has been known to make cookies using this questionable ingredient. Takers of the Homestar Quiz are treated to his recipe upon receiving a perfect score.

First seen in The King of Town DVD, it shows up whenever The Poopsmith is "on the job."