My first experience with computers was in "technology" class at school.
The teacher told us we had to switch off the monitor then turn off the computer.
Once, I forgot about this and did the other thing around, and I got yelled at ... It traumatised me so much that for a few years I always did it that way, thinking that I could break something doing otherwise...

I still feel bad thinking about this and hate that teacher for such a useless trauma about a thing he didn't understand either.