Glee has sort of mainstreamed musical numbers in TV shows (they haven’t quite become a full-fledged musical yet, but some numbers have gone beyond their supposed “realistic” setting), but it’s not uncommon for shows, especially comedies, to have big splashy musical numbers. The Fox animated shows do it all the time, of course, and How I Met Your Mother‘s 100th episode will have a production number for Neil Patrick Harris’s Barney, celebrating his love of suits.
Live-action shows usually have to have some excuse for the number — like a dream, or performing on a stage, or that Buffy the Vampire Slayer singing demon thing — while animated shows feel free just to let the people sing. But there have been a few live-action TV episodes where there is no setup or excuse provided, where characters just start singing out of nowhere, like in a musical. The only example that comes to mind right now is one of the ultimate WTF!? moments of TV, from the last and worst season of Laverne and Shirley (the season without Shirley), an episode involving Laraine Newman, Anne Ramsey, a guest singer named “Ernie Banks” (a different Ernie Banks from the baseball player) and some lip-synching that’s impressively bad even by Glee standards.
Are there any other non-animated TV episodes you recall where a musical number just happened, without any explanation or rationale?