Who used this before? Can you tell me how it works?

I was wondering on pranking my friends. Can anyone tell me how this works? Is it safe to use?





http://img383.imageshack.us/img383/3497/bloodcapsulescn7.jpgWho used this before? Can you tell me how it works?
they are safe, they make a foamy red substance when mixed with salivaWho used this before? Can you tell me how it works?
They are probably pretty save to use. However, a bit of tomato sauce or ketchup might also do the trick, and this might be less expensive.
There is a powder inside which reacts with your saliva and thus makes your saliva blood red and foamy. Seemed to recall as a kid they were not up to much but maybe technology has made them better.
they're cheapo capsules..go to a costume or party store...they will have the proper stuff you need for fake blood

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