I didn't even know Danny Boy until I intentionally learned it last month...no one does it any more because everyone kept asking for it.
Now I'll do it for little old ladies and a twenty. :) People find out you are doing it, and you'll have to do it all day long.
I sing the first part of it just before we go into the version above and you can see people go, "Ahhhhhhh." Then we get into the other version (above) and sometimes people really get upset. :)
Maybe we should start a Danny Boy thread and see what happens...or has that been done? ;)