In Robert Heinlein's novel "The Puppet Masters", alien bugs are mind-controlling a large number of the population by attaching themselves to the outside of the body. Cities still controlled by regular people are determined to stay that way. They institute 'Operation BareBack' and 'Operation Sun Tan', where everyone has to go around showing that there are no bugs on them. Paranoia sets in, so that anyone wearing clothes 'must be' alien-controlled.
Quote from the book:
I started to put my shorts back on and the first cop stopped me: "Hey, you looking for trouble? Leave 'em off."
I said reasonably, "You've searched me. I don't want to get picked up for indecent exposure."...
"You won't get picked up for indecent exposure; you'll get picked up D.O.A. The Vigilantes are a lot quicker to shoot than we are." He turned to Mary. "Now, lady, if you please."
