how do i get a mac os/ os x "live" cd like the linux "live cd?

i know it exists i have seen it but do not know how to get it and want to know how to get mac os/ os x i know it comes in both i would like either i do not prefer as of now. i would like to try mac and not get rid of my os right now and a "live" cd or livedistro would do just that. yes just like the popular knoppix "live" cd for linux.
where do i get it?
how do i use it?
have you used it?