We also had Wacky Wednesday, in honor of the book by the same name. (Although it's not a true Dr. Seuss book, I did explain to the kids that it was written by the same man using a different name.)
The book is filled with silly things that the kids have to find on every page, so for art they drew their own wacky pictures. Then they shared them with the class so we could all find the silly things.
Multiple suns was a common one, as well as floating things, like cars and trees.