fluff lines

fluff (one's) lines

To forget or bungle the words that one is supposed to say, as in a speech or play. My mind went completely blank as soon as I stepped on stage, and I totally fluffed my lines. I had learned the speech off by heart, but I was so emotional that I started fluffing my lines about halfway through.
See also: fluff, line
Farlex Dictionary of Idioms.

fluff one's lines

 and blow one's lines; muff one's lines
to speak one's speech badly or forget one's lines when one is in a play. The actress fluffed her lines badly in the last act. I was in a play once, and I muffed my lines over and over. It's okay to blow your lines in rehearsal.
See also: fluff, line
McGraw-Hill Dictionary of American Idioms and Phrasal Verbs.
See also:
  • blow (one's) lines
  • fluff (one's) lines
  • muff (one's) lines
  • muff
  • one's mind went blank
  • (one's) mind goes blank
  • go blank
  • a blank check
  • blank check
  • cheque