I have no idea. That confused me when I first read it, too.
And to add to the Seuss porn list:
I Can Fuck 30 Tigers Today!
Mr. Brown Can Screw! Can You?
And To Think That I Saw It On Mulberry’s Teat
I Had Trouble In Getting Solla To Screw
Green Eggs and Anal
Would you do it on a plane?
Would you do it in a train?
Would you do it on a boat?
Would you do it with a goat?
