The other day, someone mentioned this phrase as a NOOB. I checked and saw I had not yet covered it. The reason, I realized, is that at this point it’s so common in the U.S. that I don’t really think of it as a British in origin. (“The tone of the show, in what I have seen, is over the top “– New York Times opinion writer Kara Swisher, on the upcoming TV series Super Pumped, yesterday.)
But a Britishism it is. The OED labels the phrase “chiefly British” and defines it as: “To an excessive or exaggerated degree; beyond reasonable or acceptable limits; too far.” The OED also notes another, earlier meaning of “over the top,” stemming from World War I trench warfare: to literally climb over the top of a trench or parapet and go into battle. This took off in America, generating (as listed in the Library of Congress) no fewer than six popular songs called “Over the Top,” plus this one:
The phrase seems to have taken on a positive figurative meaning, akin to “going all out,” as seen in this item from a 1918 issue of The Rotarian:
The OED‘s first citation for the phrase with the “excessive” meaning is in a 1935 letter by the American writer Lincoln Steffens: “I had come to regard the New Capitalism as an experiment till, in 1929, the whole thing went over the top and slid down to an utter collapse.” But I take that as an outlier — a fresh metaphor on Steffens’s part, not his use of a phrase that was in currency. The first definite example I’m aware of comes from a 1965 novel called The Concrete Kimono (cited in Green’s Dictionary of Slang): “I seem to recall your ‘over the top’ waistcoats.” The quotation marks suggest unfamiliarity and recency.
By 1982, the phrase was popular enough in Britain to spawn an acronym. From The Sloane Ranger Handbook: “OTT adj. Over the top—outrageous. Usually ‘absolutely’ or ‘totally OTT’.”
It’s difficult to use Ngram Viewer and the other databases I normally consult to track the progress of this phrase and its relative frequency of use in Britain and the U.S. That’s because searches for “over the top” yield a great deal of noise: references to climbing over the top of a hill, sprinkling sugar over the top of a cake, and so on. Lynne Murphy suggested slipping an intensifier before the phrase; taking a cue from the Sloane Rangers and searching for “totally over the top” in Ngram Viewer worked nicely:
It’s a classic NOOB graph. In fact, the only thing that surprises me is that it shows U.S. use as only about half of that in Britain.
notoneoffbritishisms.com 
By 1982, OTT was so standard, there was a late-night comedy show called OTT. There had been a Saturday morning show called TISWAS (Today is Saturday, Watch and Smile). The same team decided to do an adult version, which had occasional nudity, not usually allowed on Saturday mornings, and certainly not on kid’s shows.
I never knew that was what TISWAS stood for. Live and learn.
That’s what Wikipedia says, so it must be true. 🙂 But “tiswas” has long been a word for being in a state of turmoil, so this could be a back formation.
Yes, I dare say there are now people out there saying something is ‘completely OTT’ without knowing what it stands for.
World War I trench origin makes sense. Another word the US may have adopted then, from British soldiers or not, or from the mentioned songs. My parents (from NY, IA and MS) used it routinely since before I was born (mid century) so perhaps another example of a verbal slang usage not reflected in the written language as much. Also it could undoubtedly be attached to a variety of speculative etymologies, like over the top of a roller coaster, or hitting the thing with the sledge hammer at the carnival or whatever else.
An over the top tackle is the worst type of foul in football (soccer) and liable to break the opponent’s leg. That seems more like the sense it is used now than the trench warfare allusion.
The phrase originating in emerging from the trenches in WW1, when used as a metaphor, seems uncommon compared with “putting one’s head above the parapet” here in the UK.
The “exaggerated” meaning is still common.
TIWAS was made here in Birmingham and does indeed stand for “Today is Saturday, watch and smile”.
Incidentally, I have never encountered the word “recency” before – is it common in the USA?
I actually might have made it up.
Actually, I didn’t. There’s a well-known cognitive bias called the “recency bias” and Ngram Viewer shows it’s currently used with roughly equal frequency in US and UK https://books.google.com/ngrams/graph?content=recency%3Aeng_us_2019%2Crecency%3Aeng_gb_2019&year_start=1800&year_end=2019&corpus=28&smoothing=3&direct_url=t1%3B%2Crecency%3Aeng_us_2019%3B%2Cc0%3B.t1%3B%2Crecency%3Aeng_gb_2019%3B%2Cc0
After further research, it seems to be a technical term in both countries rather than in common use.
I think OTT is used more commonly in the UK than ‘over the top’, but maybe I am just showing my age.
Paul, your ‘word for being in a state of turmoil’: my wife says ‘in a twitter and a twotter’ – which I’ve always assumed that only she and her mother ever said, though I’ve been proved wrong before.
I don’t think I’ve ever heard that.
Incidentally, the first citation for tiswas in the OED is 1960. I’d have thought it was much older, the sort of thing a character in Dickens might say.