The letter “Y” can change a lot. Happy certainly isn’t the same as happiness. I know I get pissed when someone spells my last name without one and it seem to soften the flint of an otherwise difficult name to say i.e. Cutty, Gunny, Baby,. Starting to get the picture? It can completely change a fish to fishy. No “Y” brings about images of open seas and aquariums and the other makes you curl your nose. And let’s face it. A fair and a fairy are way off. I guess the one rule of thumb that sticks out in my mind. If you have to put a “y” on the end of class, It’s probably not.