(chiefly US, colloquial, sarcastic) An expression or exclamation that something is exceedingly obvious or apparent, or that one would have to be extremely foolish not to realize something immediately.

An area into which entry by a single individual is prohibited; commonly an area with accessibility to a nuclear weapon.

(idiomatic, litotes, understatement) Misbehaving, being mischievous.

(Britain, informal) A supposed surname for a friendless person.

worthless or of no merit / useless

One must be willing to endure some inconvenience or discomfort in order to achieve worthwhile goals.

(idiomatic) To say, do, or indicate something clearly and without hesitation, even if it may be unpleasant.

A surname.

In no case, whatever happens; never.

A declaration, in bridge and similar games, that a hand is to be played without a trump suit.