I think that old saying had a simpler meaning, in the old days. I think it just meant that with words like "Fatty fatty 2 by 4, couldn't get thru the bathroom door", did not physically hurt you. You had to let a lot of that stuff roll off your back or you set yourself up as a victim/nurd and the mean kids all teased victims/nurds.

The words have become more vicious and now, even plastered on the internet, for all to see. Kids are committing suicide because of these words!!

I always liked "I'm made of rubber, you're made of glue and those words bounce off of me and stick to you"