It's like, one extra float? ;)

For real though, I had an amazing realization in the shower one time that I could implement 3D rotation without learning linear algebra (or god forbid quaternions) by just doing three 2D rotations. A few hours later I had a rotating monkey!

Yes. You did do that. But the monkey wasn't too happy. And you have been banned from the zoo. So was it really the correct approach? ;-)

And then you discovered gimble lock, and to fix that you just need one extra float...