A replacement made at the last minute, usually in a sporting context. / An outsider.

plural of grandmother-in-law

A grandmother of one's spouse.

A grandfather of one's spouse.

plural of not the sharpest knife in the drawer

(idiomatic, transitive) to give up, to quit

(idiomatic) Relaxed and confident in one's manner of presenting oneself and interacting with others; conveying the impression that one has a clear, satisfying understanding of one's own abilities and situation.

Synonym of knee-deep in the Big Muddy

(chiefly US, idiomatic) Stuck in a predicament; mired in a difficult situation, especially one resulting from poor judgment or bad leadership.

As an exchange or replacement. / To reciprocate.