flop sweat

noun2

1. •
   (slang) Sweat due to nervousness, especially fear of failure.

   • Billy Vine, covered with flop sweat, started so-so, but in a few minutes he had them. — 1947
2. •
   (slang) Panic or anxiety about possible failure.

   • This is the point very often where panic sets in. In theatre jargon, we call it "flop sweat." — 1979