Here's an old that seems designed to instill pantswetting terror in children. I just watched it again to link it here and even knowing what was coming, I still jumped / screamed.
Here is a AIDS PSA from Australia, aired in 1987. Don't watch this before you go to bed. I am not kidding.
My friend and I were on vacation in Ireland a couple of years ago when we saw this. After a few seconds of stunned horror we turned to each other and said in unison, "They don't fuck around!"