It once Happened to me.
Playing PSN On the bus with my headphones in, when all of a sudden someone sat straight next to me, and started bugging me about how : "I've heard the 3DS can kill you or give you seizours (Escuse the baby murdering spelling)!"
As to which I reply : "I don't have a 3DS, Ma'am. Can you please stop bugging me and let me get back to my Silent Hill?"
She kept slapping my ear off about "The video-games cause violence" Bullshit.
Then she started complaining about the whole "Survival Horror is too scary" Bullshit and asked to to put it away.
I then reply "I am sitting on a turnable seat, and have headphones in. I cane easily turn it around and no sound will come out and you won't be able to see it."
And then I got a bunch of bullshit rambled to me about the whole "Video-games cause heart-attacks" Bullshit (Once again). Seem's a bit stereotypical. That's the only time I can remember, by the time I got back home she knarcked to me all the age rating's and all that bullshit and asked why a 25 (me) Year old was still playing video-games. WORST DAY OF MY LIFE.
EDIT : That never happened when I was in school, hell, even on friday for our 'Reward time' (Which we got for tolerating the bullshit about quantum physic's) there was even a gaming activity, where we where aloud to bring 3 Handheld's (I alway's brought my Gameboy) and someone would ramdomly be picked to bring a console and have it hooked up, it was usually and NES but every once in a while someone would bring a pong-machine, and even rarer someone would being a virtual boy and noone would play them since they didn't want their eyes to look like something K'thulu just tore up with a jackhammer.