Speaking of nuns descending, in kindergarten we had one who asked us to stick out our tongues and anyone with a pointed tongue was labeled a liar. I spent weeks in front of a mirror worrying if mine was pointed and trying to figure out ways to make it appear more rounded.
But for sheer psychological abuse you can't beat the Protestants. A Sunday school picnic was ruined for me when I had trouble putting clothes pegs on a clothes line during a race and ended up last. To add insult to injury the Sunday school teacher remaked to me during my struggle, "I guess this shows that you never help your Mommy!"
Oh the guilt!