“What’s My Line?” is basically a version of Twenty Questions relating to occupations. The show ran from 1950 to 1967 on CBS in the United States and had a collection of panelists from a variety of entertainment and media fields who were very skilled at the game.
Over the years a wide variety of contestants visited the show, but the Mystery Guest, a celebrity, always added excitement and fun.
There is a YouTube channel dedicated to the show and Buzzr tends to run it on its schedule.