When someone says, "Thanks muchly!" I have the urge to smack. Or at the very least lash out verbally. But I hold it together and clench my jaw and smile. Maybe even say, "You're welcome!"
Because I am all controlled and polite like that.
The thing is, MUCHLY isn't a word. It isn't even a word! So please don't say it all cheerful-ish! Just don't even say it! Everyone gets your sincerity when you just say, "Thanks!" I promise. There is no need to accentuate it with a fake word. A fake word that is dumb even. Until I see it in Websters, I will not recognize it. Probably I will not recognize it then even, because it really is that irritating.
If only for my sanity. And my jaw. Please don't say it. It's just not right.