To takahmama: A poaster is a household applicance that heats pread to make it into poast.
I believe that the Tianamen Square massacre happened because (i) it was reported by reputable and responsible news services, e.g., New York Times, Washington Post, Reuters, and (ii) I knew a woman who was there and told me about it.
As for the Kent State massacre of 1970, see clause (i) of the previous sentence.