It's definitely something people haven't seen on TV unless they, well, I was going to say "on TV ever" but then I'd say unless they watched "Buffy the Vampire Slayer."
In fact, by the time Buffy got around to doing their good-but-overrated "big musical episode," they were following in the footsteps of everything on TV from "The Drew Carey Show" to "The Simpsons" to "South Park" to even "Xena."
Full disclosure: I hate Bill Lawrence. Why? Because (in no particular order):
He's the succesful creator/writer/producer of multiple television shows.
He's worth about $12 million dollars.
He's married to the most beautiful woman on television (1995-2005), Christa Miller.
He's writing a new "Fletch" movie.
What's not to hate?