Stan Laurel and Oliver Hardy were known for their physical comedy, but they had their share of fun with language, too. In one scene in the 1931 short “Our Wife,” Ollie is trying to make Stan understand that his planned elopement is supposed to be a secret: “Nobody must know about it. It’s strictly on the qui vive.”
What he was trying to say was “on the q.t.” (The right phrase wouldn’t have helped Stan, of course.)
In this phrase, which means “quietly” or “secretly,” “q.t” is simply an abbreviation of “quiet.” According to “American Slang,” its first recorded appearance was in 1884.
“Qui vive,” on the other hand, is a French phrase used by sentries, a form of “Who goes there?”
What it’s really asking is “Whose side are you on?” — literally, “Long live who?”
I suspect the penalty for a wrong answer could be severe.