Keeping an idea open source - How?

[em2nought]

So if you have an idea for something, but you want anybody and everybody to be able to use it/create it and don't want someone to patent it is there a cheap way to do it? Also is there a way to protect yourself in case some dumb ass hurts themselves or others with said idea?

[Kasey Chang]

If you release it outright, and put it PD, no one can patent it because it'd be ruled "prior art".

That doesn't stop anyone from making a minor tweak to it and claim it as an invention though.

[Kraken]

If it's a change-the-world kind of invention, patent it with universal free access. That sounds like it ought to be a thing.