Curmudgeon (ker-muhj-uh-n)
noun
A bad-tempered, difficult, cantankerous person.
"After scolding the children for playing too loudly, Edgar realized he'd become the old curmudgeon he'd despised as a youth."
Alternate definition:
noun
A cupcake, muffin or other pastry that has been smashed or mushed out of anger or spite.
"Derek stormed out of the office breakfast meeting, slamming his fist on the buffet spread on his way out leaving behind a nearly-full box of curmudgeons."