Whistling in a theater is considered bad luck because it was once a signal to drop heavy scenery.

The tradition of hiring sailors as stagehands dates back to the 17th and 18th centuries when theaters began using complex rigging systems. Sailors were preferred because they were experts at handling ropes, pulleys, and knots, which were essential for operating the heavy hemp-rope fly systems used to move scenery. These maritime workers brought their shipboard communication methods to the stage, specifically using coded whistles to signal when to raise or lower equipment.Because theaters were often noisy and dark, a sharp whistle was the only way to cut through the sound of a performance to reach workers high in the rafters. If an actor or a visitor whistled on stage, the stagehands might mistake it for a cue to release a sandbag or a wooden flat. This mistake could lead to catastrophic accidents or even death for those standing below on the stage floor.One of the most famous examples of this danger is associated with the 'curse' of Macbeth, though the whistling taboo applies to all theatrical productions. Over time, as mechanical and electronic communication replaced whistles, the practical safety rule evolved into a widespread superstition. Today, many professional theaters still forbid whistling in the wings or on stage to respect this long-standing tradition of safety and professionalism.