Sorry, that's just been in my head all morning. Consequently, today's doodle is a throwback to my childhood, when a little nuclear ooze was all you needed to have ninjas in your sewers.
Interesting side note: Cowabunga actually originated as a catch-phrase greeting of an indian named Chief Thunderthud on the Howdy Doody show. This information could one day save your life. I'm here to help. You're welcome.
Tomorrow, ADVENTURE!! :)