The 76 Trombones

Origins
The song Seventy-Six Trombones  was the signature song from the musical The Music Man, written by Meredith Willson in 1957. Though the original song did not include the vast amount of trombones indicated, the first "Meredith Willson Variety Show" featured a performance of this song by Sergio Franchi backed by four military marching bands, carrying exactly 76 trombones between them.

Effects
Playing one of the Trombones will cause the rest to play on their own, floating in the air in parade formation behind the player. After the first verse, and entire marching band of instruments will begin playing the song, though the instruments themselves will never seem to be present. Anyone who sees the procession will be compelled to march until the song has been played seventy-six times, or until seventy-six miles have been marched.