Idiom meaning "Why are you in a bad mood?", implying discontent with the other person's attitude. As it is a rhetorical question, no response is expected. Often used in situations where the person being asked is angry as the result of an underlying cause and therefore snaps at people who have nothing to do with this cause.
A source of contention between Norwegian black metal musicians. To declare your preference for "soft" or "soggy" cornflakes is to express a desire to branch out as a musician and explore the possibilities of artistic maturation. To steadfastly swear allegiance to crispy cornflakes is to commit to stabbing your musical rival in the head and committing arson.
The topic of cornflakes can also be usefully employed to deter metal guys from boring you with their inane banter.