I watch NCIS for years, and was always sure the "elevator trick" (aka Elevator Conference) Gibbs is doing sometimes (stopping the elevator in the middle of its ride without actually ringing any bells or summoning a rescue) was invented by that TV show, e.g. here.
However, few days ago I noticed it was already done nearly 20 years ago, in Friends! (S06E08)
So my question is: what is the first appearance of such a thing in a TV show or a movie?