Change the "y" to an "i" and add an "er" or an "est"

Mo was having problems with his spelling homework and I was trying to help him.

Many of the words were things like "happier" or "sillier" and "sorriest".

I told him to think about the root word -- happy, silly, sorry -- to listen for the long e sound and to think about if it was spelled with an "e" or a "y".

If it was a "y", you change the "y" to "i" and add an "er" or an "est".

I know that all rules of English grammar and spelling are broken (i before e, except after c or when it sounds like an a like in neighbor or weigh or some weird shit like that).

While taking my shower I tried to come up with words that broke the rule but my mind is crappy, crappier, crappiest, this time of night.

I know there has to be a word that breaks the rule!

Please tell me what it/they is/are!

Thanks!