A convention of British drawing room comedies and certain novels of the 1920s and '30s was a brainless but good-natured upper-class twit—think P.G. Wodehouse's Bertie Wooster—who would appear in white flannels (de rigeur for tennis in those days), brandish his racquet, and inquire among the other weekend house-party guests, “Anyone for tennis?” The phrase caught on, as such mindless clichés are wont to do, and decades of wannabe-clever young men on both sides of the Atlantic who felt obliged to say something—anything—would ask, “Tennis, anyone?” even if there weren't a court within miles . . . and then they wondered why no one laughed.
See also: tennis