There's an Easter egg on Disc 1 of the "Star Wars III: Revenge of the Sith" DVD, and it's found in the same way as the Easter eggs on the DVD's for Episodes I and II.
Insert Disc 1, navigate to the OPTIONS menu, then use the arrows to highlight the THX icon. Then punch in the number 11, followed by the number 3, followed by the number 8. Exactly how you punch in the numbers may vary slightly depending on your equipment, and punching in the two-digit number 11 will probably require that you first press something like a 10+ button or a greater-than-or-equal-to-10 button on your remote. (On my oldest DVD player, I have to press the Enter button after each of the three numbers, but my two newer players don't require this.)
If you do everything as required by your particular equipment, you will see Yoda make some hip-hop moves to "Don't Say Nuthin'" by The Roots. That will be followed by the DVD credits.