the.com/opening act

The job of making a crowd impatient for someone else.

means The performer, speaker, or event that goes on first to warm up an audience before the main attraction appears.

from Pulled straight from the structure of a stage bill — 19th and 20th-century vaudeville and concert programs listed performances in order, with lesser-billed acts 'opening' the show before the headliner. The phrase migrated out of theaters in the 20th century to describe anything that precedes and sets up a bigger event — a warm-up speaker, a preliminary negotiation, even a minor crisis before the real one hits.

origin
Vaudeville used openers to fill seats early
risk
Boo too loud and the headliner hears it
notable
Jimi Hendrix once opened for the Monkees
irony
Sometimes the opener outlives the headliner's fame
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