Appears on a plane on Main Page 3 and on a ship on Main Page 15. If it's anywhere else, please add!

It is in the StrongBadEmail/island, when Homestar says "Hey Strong Bad, look at this! Toons! Games! E-mail!"
- That's the email. ^

It's in the quiz, The question that asked what the airplane in Main Page 3 said -Crap

It's hard to tell, but the ship that it appears on in Main Page 5 also speeds by on Homsar's Mainpage
Metastar [Metastar's fansite]