He was an extrovert and a character,again like his mother, with a knack for tossing off the perfect bon mot. Once at a dinner party, he told his seatmate, “We are all worms. But I do believe that I am a glow-worm.”
Craig Shirley, December 1941: 31 Days That Changed America and Saved the World, 2011
You need not hurry when the object is only to prevent my saying a bon-mot,for there is not the least wit in my nature. I am a very matter of fact,plain spoken being, and may blunder on the borders of a repartee for half an hour together without striking it out.
Jane Austen, Mansfield Park, 1814
Bon mot is a borrowing from French,translating literally as “good word.” Theterm entered English in the mid-1700s.
Source: dictionary. com