Smoke-Filled Room

A phrase from mundania, where it originally described the room in Chicago's Blackstone Hotel where a small group of powerful United States senators gathered to plot the nomination of Warren G. Harding as Republican candidate for president in 1920. Once newspapers picked up the expression, it became synonymous with offstage political intrigues.

Fans used it similarly, to describe the meetings of smofs at closed-door parties, which were often quite literally smoke filled. Now that hardly anyone smokes anywhere, and you have to go outdoors to do it if you do, the phrase has fallen into disuse.

from Fancyclopedia 2 ca. 1959
Originally the term for the behind-the-scenes activity concerning voting on the following year's consite, by analogy with the SFR of political conventions. But now it simply designates any hotel room where fans gather during a convention to drink and discuss.