Alyson Hannigan

Repeat After Me. Catchphrases are the new punch lines.

How I Met Your Mother, on CBS, is a charming, smartly crafted sitcom; it’s also the most catchphrase-happy show on TV. The characters, led by the wiseacre Barney (Neil Patrick Harris, pictured), fling undercooked phrases at the screen just to see which ones will stick. Along with Barney’s twin battle cries, “Suit up!” and “Legendary!,” the show has field-tested, in one episode alone, “the lemon law” (a five-minute rule for rejecting a date), the “self-click” (clinking your own glass for a toast no one accepts), and “bro-by-extension” (your best bud’s fiancée). This isn’t a comedy, it’s a televised glossary.

It used to be enough for a sitcom to launch one lunchbox-friendly catchphrase, be it “What you talkin’ about, Willis?” or “Dy-no-mite!” In fact, that corny, here-it-comes moment when an actor turns one eye to the audience became such a cliché that shows in the eighties, like Family Ties and Cheers, steered clear of self-conscious coinages. Then came Seinfeld. The show’s main joke-venerating minutiae-turned it into a catchphrase factory: man-hands, sponge-worthy, not that there’s anything wrong with that, etc. Or rather, yadda yadda yadda.

How I Met Your Mother takes this approach to a ludicrous extreme-which, it turns out, is both funny and a canny act of self-preservation. Blogs and online forums are written in an ever-evolving patois, stitched together from inside jokes between fans. (The Simpsons alone has spawned its own quasi-language.) So a catchphrase that actually catches on can make a show part of the cultural conversation, literally and instantly. Back when sitcoms had a whole season to find an audience, they could afford to lure people in with funny characters. Now shows have about two episodes to hook you, and catchphrases are much flashier bait. The catchphrase-as-punch line is simple evolution: It’s survival of the glibbest.