Day 20 is a Blaxploitation Horror-themed day, but I was afraid we might not find something for you along those lines. Dr. Black and Mr. Hyde--can't find the full film. You can get Blacula on Hulu, but Hulu is stingy about worldwide viewing rights. Even Blackenstein, the film we all enjoyed together at this time last year...has been taken down.
Where to turn? To one of the most utterly mental sci-fi films ever created. The tagline was "They transplanted a white bigot's head onto a soul brother's body!" The bigot was played by Ray Milland and the soul brother in question was played by Rosey Grier. Why Ray Milland? No idea. Why Rosey Grier for that matter...he'd made a slew of television appearances before debuting on the big screen in 1972 in Skyjacked and then appearing the same year in this. Very odd indeed. Speaking of very odd, if you've never seen this before you're in for a treat of massive WTF proportions.
It's available on DVD as a double-feature with The Incredible Two-Headed Transplant from Amazon.