There is no such thing as toxicity. A toxic substance is only toxic to a given system. Therefore we are mistaken if we identify the system-given property of “toxicity” with a particular substance, or example of such a substance.
If we are to accept that the property of toxicity can therefore be culturally conferred on particular substances (or examples of such substances), then obviously the property of toxicity can be conferred on any substance. Therefore any substance can be regarded as toxic.
This being the case it is perfectly OK to drink poison, as everything is toxic anyway and most things we drink have no harmful effects, thus disproving the entire idea of toxicity.
Of course even if we accepted the ridiculous idea of toxicity, we’d have to work out what the word “poison” refers to in order to actually find some to drink, assuming that words can actually refer to anything, which obviously they can’t, except in essays by postmodern “thinkers”.