The phrase never a dull moment designates:
– (in literal use): constant variety or interest;
– (in ironical use): constant variety of troubles, difficulties, etc.
This phrase occurs, for example, in the following about the then Prime Minister of the United Kingdom, Boris Johnson (born 1964), published in The Independent (London, England) of Friday 17th June 2022 [page 2, column 1]:
Setbacks, scandals and disasters… all in a day’s work for our flawed PM
One of the few things that the prime minister’s friends and foes might find common ground on is that there’s never a dull moment with Boris Johnson. Not, it must be added, always in a good way. Indeed, pleasant surprises about Mr Johnson seem to be something of a rarity.
The texts containing the earliest occurrences of never a dull moment that I have found indicate that, in literal use, this phrase originally referred to theatrical performances—these early occurrences are as follows, in chronological order:
1-: From a review of Her Majesty’s Ship Pinafore, produced at the Broad Street Theatre, published in The Philadelphia Inquirer (Philadelphia, Pennsylvania, USA) of Tuesday 25th February 1879 [page 4, column 5]:
There has never been a weary face in the audience, never a dull moment in the house while Miss Chapman has been upon the stage. She is so hearty and earnest in all she does, so ambitious to excel, so eager to evoke pleasurable emotions, so determined to compel the good humor of her audience, that her success is assured from the moment of her appearance.
2-: From a review of The Strategists, produced at Ford’s Opera-House, published in The National Republican (Washington, District of Columbia, USA) of Monday 6th October 1879 [page 4, column 5]:
“The Strategists” is full of irresistibly laughable situations, and there is never a dull moment from beginning to end.
3-: From a review of A Scrap of Paper, produced at Wallack’s Theatre, published in the New-York Tribune (New York City, New York, USA) of Tuesday 6th January 1880 [page 4, column 6]:
This, in fact, is a model piece. There is no flaw in its texture; there is scarcely a defect in its basis; there is never a dull moment in its progress; and there is no cloud on the rosy cheerfulness and wholesome thought of its effect.
4-: From a review of Aladdin, a pantomime produced at the Theatre Royal, Brighton, published in The Era (London, England) of Saturday 12th February 1881 [page 17, column 4]—reprinted from the Gazette of Thursday 30th December 1880:
“Miss Lillian Francis plays Aladdin with great spirit. There is never a dull moment when she occupies the boards, and her impersonation is in every way charming.”
5-: From a biography of the French actor, singer and stage manager Claude Marius Duplany (1850-1896), published in The Stage (London, England) of Friday 2nd September 1881 [page 8, column 1]:
We also hope that M. Marius will remain with us for a long—a very long time to come, for we can ill afford to lose this buoyant actor and finished artist. He is ever full of life and animation, and overflows with good spirits and lively humour. There is never a dull moment whilst he is on the stage, and altogether he is one of the best and most successful comedians that we have.
The earliest ironical use of the phrase never a dull moment that I have found is from the following passage from Three Men in a Boat (To Say Nothing of the Dog) (Bristol: J. W. Arrowsmith, 1889), by the British author Jerome Klapka Jerome (1859-1927) [chapter 9, page 141]:
Of all experiences in connection with towing, the most exciting is being towed by girls. It is a sensation that nobody ought to miss. It takes three girls to tow always; two hold the rope, and the other one runs round and round, and giggles. They generally begin by getting themselves tied up. They get the line round their legs, and have to sit down on the path and undo each other, and then they twist it round their necks, and are nearly strangled. […]
[…]
There is never a dull moment in the boat while girls are towing it.