My cat Rex is 2 yrs old and any time I use bleach on the floors, counters, sinks, he rolls around in it like catnip, just like all the other cats. I'm glad to hear it's not too dangerous for them to do this, he only does it for a minute or so. Of course I remove him and don't let him lick it! Like most of you, I wonder if chlorine has some type of pheromone effect... It definitely looks like it causes endorphins to be released. Anyway, I'm really glad to find out my cat isn't the only one. I really thought it was weird the first time I saw him do it as I've had many cats during my life (yes, I'm a cat lady, 2/3 of them at a time) and this was the very first time I'd ever seen this behaviour.
Thanks!

Don't worry my cats do this too but only some cats do it not all some hate the smell of bleach and chlorine the only thing I would do is not too let him drink it as I think if they get it inside there body it can sometimes be poisoisnes.