Brannigan's Law

Here is a work in progress...a little cartoon I drew in response to Nancy's demands that I draw her a turtle...
It is still very rough. Hopefully the finished product looks sharp and clean. Again, this is just to become more familiar with drawing using the Wacom Bamboo Fun tablet.
Any guesses as to what the joke will be? It's pretty obvious...to me....but then again, I thought it
up. Very rough looking, I know. A little too long...I'll crop it at the bottom and move the starfish and the seaweed up a bit to compress everything a little and get rid of the dead space. Man I think 'shell-less' turtles are funny looking...