I use the fork with the prongs turned downwards to "stab" the food and put it in my mouth. I never balance food on top of the prongs because it's bound to slide off and land in my lap!
What gets me is when people leave bits of food smeared all over the plate when they have finished eating. I was taught to scoop all the food up properly so as to leave the plate as clean as possible when I had finished.
Being quizzed by chemist's assistant in Boots.