verb (used without object)
1. to be sulky or morose; show discontent; complain, especially in an irritable way.
Don’t we all have those days when pasting a smile on our face just seems like way too much trouble. Well, for one day you don’t have to struggle to keep that happy expression in place. Today is National Grouch Day. A day when we can all let out our inner grouch. Enjoy it while you can and grouch away. Just don't go overboard. Remember tomorrow, you may have to eat your words.
“A grouch escapes so many little annoyances that it almost pays to be one.”