Vaudeville bosses had strict ideas about what was acceptable language and behavior on its stages. Today we still refer to something risqué or naughty as being “blue.” Here’s why:

“Between the (Monday) matinee and the night show the blue envelopes began to appear in the performers’ mailboxes backstage … Inside would be a curt order to cut out a blue line of a song, or piece of business. Sometimes there was a suggestion of something you could substitute for the material the manager ordered out … There was no arguing about the orders in the blue envelopes. They were final. You obeyed them or quit. And if you quit, you got a black mark against your name in the head office and you didn’t work on the Keith Circuit anymore. During my early years on the Keith Circuit, I took my orders from my blue envelope and — no matter what I said or did backstage (and it was plenty) — when I went on for the Monday night show, I was careful to keep within bounds.” – Sophie Tucker, Some of These Days

Learn more about Sophie Tucker.