And they never buy the house with clothes in the closet.

Dear Word Detective: I remember hearing people say that such and such behavior seems like “bad pool”– meaning that it seemed underhanded or sneaky. Yet I find very few examples of the phrase on a Google search, and no discussions about the origin or meaning of the phrase. Is it even a real expression, or did I just mishear something? And if it is for real, why is it so rare? And where did it come from? Thanks for any info you can provide! — David A.

Whoa. You and me both, dude. I’ve just spent about ten minutes staring at your question and racking my brain about “bad pool.” I thought it sounded familiar, and I instinctively knew what it means, but I couldn’t remember ever actually hearing the phrase. It’s a creepy sort of feeling, as if someone in your family just referred to a sibling you never knew you had. The worst part was that this sort of thing has happened before. About 15 years ago, in answering a reader’s question, I convinced myself that the verb “stinch,” meaning “to be cheap,” not only existed, but that I had actually used it as a child. It doesn’t, and I didn’t. I was, in my garbled memory,  apparently combining “stint” (meaning “to cut short or restrict”) with “stingy.”

In this case, the phrase you are thinking of (and which I was temporarily unable to retrieve  from the sticky sludge of my mind) is not “bad pool,” but “dirty pool.” You may indeed have heard “bad pool” at some point, but “dirty pool” is definitely the common form of the phrase. Yup, “dirty pool,” and there’s no need to take away my car keys just yet.

The “pool” in the phrase “dirty pool” is not a puddle of unsanitary water, but the game of pool, played with cues and balls on a rectangular table with raised, cushioned edges. “Pool” takes its name from the Old French “poule,” and was originally a card game (with a “pool” of stakes in the middle of the table). “Poule” is also French for “hen,” and the theory is that if you trace “pool” even further back, you’ll find a Medieval game that consisted of throwing things at a chicken. Seriously.

By the way, for you HGTV “House Hunters” fans, if the home buyers inspect a house containing a pool table, that’s the one they’ll finally “pick” (they’ve actually already bought it). The same table will appear in the “after” shots, often accompanied by a little fable about how they bought it from the previous homeowners. Now turn off the TV and go play outside.

The “dirty” in “dirty pool” is the adjective used in its sense of “morally unclean,” as in such  now-antiquated phrases as “dirty movie.” In the mid-18th century “dirty” first appeared in the sense of “earned by dishonest or despicable means,” and by the early 20th century, “to do the dirty” meant “to play an underhanded trick” (“The Germans have been ‘doing the dirty’ on us by donning khaki and kilts to approach our trenches,” 1914). “Dirty trick” employs the same “sneaky, underhanded” sense of “dirty.”

So “dirty pool” refers to a game of pool, and by extension nearly any endeavor, conducted in a dishonest, dishonorable fashion, especially by lying, cheating or exploiting an unfair advantage. “Dirty pool” first appeared as an idiom meaning “unfair tactics” in Herman Wouk’s 1951 novel The Cane Mutiny (“I played pretty dirty pool, you know, in court”), and remains widely in use today. The phrase carries a strong connotation of disapproval, i.e., the tactic being described as “dirty pool” would be beneath the dignity of a decent person (“If Russia badly needs food to replace crops ruined by the nuclear plant accident, should the U.S. use its surplus food as a weapon? … No. That would be dirty pool,” 1986).