I did it in my head first. I can't get the link to work so I thought it was a trick.
is part of a discussion in the Funny Stuff: Jokes, Quizzes, Games & Pics forum that includes topics on Big penis jokes, small penis jokes, amusing anecdotes.
Aw, hell, I'm never any good at this one. There's a couple of the same kind of puzzle in a Nintendo DS game called Professor Layton and the Curious Village, and I just about give up on them.