I have no idea why this occurred to me, but . . .
Some years ago I was playing in a now-defunct bar called "Olde Grads." The band was positioned on a stage behind the bar. Looking past the backs of the bartenders, you saw shapes in a haze moving, dancing, drinking. The smoke was so thick in the place that the stage lights created solid curtains of color when they flashed.
One night, I was feeling particularly (and literally) sick of the smoke. As the drummer, I was farthest back, up against the wall. I saw a switch. Wondering what it would do, I flipped it. Immediately, the smoke cleared from the bar. It was an exhaust fan. The bartender (a guy who, I am sure, had left a few horse-heads in the beds of transgressors) whipped around with a crazed look on his face. As he searched for the cause of the clear air, he smoothed back his gray hair, chewed furiously on his soggy cigar and uttered the most unspeakable profanities. "Who the ____ turned on that _____ fan?"