Don't Mix Ammonia with Bleach

Ammonia and bleach are two common household cleaning products. Do not ever mix them as it creates a gas that you will choke to death on.

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Don't mix ammonia with bleach!!!

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The primary toxic chemical caused from the reaction is chloramine vapor, and possibly a hydrazine formation. (Yes it says chloramine and not chlorine)

What to Do If You Mix Bleach and Ammonia - First Aid

If you do accidentally become to exposed to fumes from mixing bleach and ammonia, immediately remove yourself from the vicinity to fresh air and seek emergency medical attention. The vapors can attack your eyes and mucous membranes, but the biggest threat comes from inhaling the gases.

1. Get away from the site where the chemicals were mixed. You can't call for help if you are overwhelmed by the fumes.
2. Call 911 for emergency help. If you really don't think it's that bad, then at least call Poison Control for advice on handling the after-effects of exposure and cleaning up the chemicals. The number for Poison Control is:1-800-222-1222
3. If you find someone who you think has mixed bleach and ammonia, chances are he or she will be unconscious. If you can, remove the person to fresh air, preferably outdoors. Call 911 for emergency assistance. Do not hang up until instructed to do so.
4. Thoroughly ventilate the area before returning to dispose of the liquid. Seek specific instructions from Poison Control so that you don't hurt yourself. You're most likely to make this mistake in a bathroom or kitchen, so leave and seek assistance, return later to open a window, allow time for the fumes to dissipate, and then go back to clean up. Dilute the chemical mixture with plenty of water. Wear gloves, just as you would for either bleach or ammonia.

Source: http://chemistry.about.com/od/toxicchemicals/a/Mixing-Bleach-And-Ammonia.htm