I think you are unlikely to die through eating quiche that is two days past its best, unless of course you choke on it...might be best to read the thread about shitting through the eye of a needle before you have another mouthfull.
You should be alright if the quiche (more manly to refer to it as a cheese flan btw) has been kept in the fridge. However if has been left festering in a cupboard you may experience the shits. Have plenty of bog roll at hand , if you do get food poisoning you will be passing liquids from arse and mouth on a regular basis.