(sometimes proscribed) He or she; used as a gender-neutral reference to the third person singular.

(colloquial, rhetorical question) Alternative form of am I right, implying the speaker can't possibly be wrong.

Alternative spelling of exclusive or

plural of trick-or-treater

(idiomatic, set phrase) At this sole opportunity, or not at all.

(idiomatic) Regardless of what the circumstances are, and how the weather is.

(idiomatic, chiefly in the negative) Logic; common sense.

(chiefly US, idiomatic) An expression suggesting an ultimatum which indicates the listener(s) will either conform to the desires or teachings of the speaker or else be excluded.

Modifications, limitations, or addenda; qualifications of any kind; speculations about whether a particular idea or enterprise is good.

Either dead or alive. / Used to indicate someone is being sought for some kind of punishment or reprimand, and that (s)he may be killed in the process of finding, as if this was reasonable punishment.