^ I did that once myself, in a tiny little bathroom. It was my first apartment, I was not the most experienced when it came to cleaning. I put some blue toilet bowl cleaner in the toilet, then added some bleach. "Look at that, the bleach eliminated the blue color" So of course, I added more of each until the fumes knocked me on my a**. I crawled out of the bathroom and was lucky enough to catch my breath, my girlfriend was home too.

That's just one of the stupid things I have done.