wet one's whistle

Idioms  

1. Have a drink, as in I'm just going to wet my whistle before I go out on the tennis court. This expression uses whistle in the sense of “mouth” and may allude to the fact that it is very hard to whistle with dry lips. [Late 1300s]

---

Example Sentences

A superstitious practice among old seamen, who are equally scrupulous to avoid whistling during a heavy gale.—To wet one's whistle.

From Project Gutenberg

This was a serious matter, for in a region where coffee and tea are almost unknown luxuries, and the evening meal consists of such thirst-provoking articles as broiled venison, corn-dodgers, and sorghum, one is apt to feel the need of some liquid milder than "apple-jack," and more toothsome than water, wherewith to wet one's whistle.

From Project Gutenberg