One of the most common statements from those who deny Evolution is: "How could something so complex start from something so simple?" Part of the difficulty lies in the inability for most folks to fathom millions of mutations over millions of generations.
This below video does a great job of demonstrating how, over time, something simple can evolve into something unrecognizable. The premise is simple: One person draws a straight line. The next person is asked to trace the previous line. And so on -- like a game of Telephone. Although this model doesn't actually demonstrate how evolution works, it is remarkable in its ability to distill a simple evolutionary idea into something compelling and eye-opening.