Sounds like you went to the same school that I did.
No. I went public, myself. Friends who were not so, er, lucky, would tell tales of the nuns at their parochial schools; most not as dramatic.
Here's the key, though: it ONLY TAKES ONE really good story like that, to keep several successive years of students in line. A little help from a few key administrators could keep a rumor like that alive for decades.
A little fear of the not-quite-totally-known goes a very long way, indeed.