I found this picture in the Vintage Usenet Newsgroup. My guess is that it was taken during one of the frequent crackdowns on obscenity that took place in the US during the 50s. Probably the word “Burlesque” was targeted, but this is just my guess (and you can put yours in the comments).
Still, as I believe sex is like politics, I like the idea of sexual demonstrations, with marching and signs (my favorite today would be: “Missionary is killing sex!“). For a historical perspective you can read Kitty Klaw’s History of Burlesque Theatre.