I just started Animation Mentor a couple of weeks ago. While watching one of the lectures, I had the idea to do a crappy little animation of a blobish thing, but doing every frame manually (with no interpolated keyframes).

I did it just for fun, no planning or anything (I was way too tired to sketch stuff out). I found doing all the frames manually was actually easier; if I had used keyframes I would’ve had to spend a lot of time planning things out for the same result.  I also really like the feel of animation done primarily on twos, something you don’t see often in CG.