The switchman examined the switch again, checking that the express had done no damage, then went into his cabin, pulled the door to, and played a few notes on his signal horn.

NEWYORKER: Among Animals and Plants

Fyodorov played a long welcoming note on his horn to signal that the section was ready for the train to enter, and respectfully held his lantern out toward the engineer, his unknown friend, the only person who was aware of him at that moment, and who would be pleased that all was as it should be.

NEWYORKER: Among Animals and Plants

The fighting starts when a signal such as an air horn or whistle blows, and can last anywhere from a few minutes to a few hours.

BBC: Get rowdy at International Pillow Fight Day