The Shakespeare Sketch
Please note that this is not officially a Blackadder special; this has been confirmed by the show's creators. But I like to keep it on here as the main character (not Shakey) is very Blackaddery in nature.
This sketch was performed on stage for an AIDS benefit concert directed by Stephen Fry on September 18, 1989. Rowan Atkinson's character is unnamed, but from the look of him, it seems he's a member of the Blackadder family. The other character, whom you will know, was played by Hugh Laurie.
The sketch was available on a video called Hysteria 2 - The Second Coming, although it has been deleted for some time now. If you are looking for a copy, I suggest you check out the wonderful site that is eBay.
Anyway, here's the sketch in all its glory.