1
general::
Phrase(s): 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.
McGrawhill's American Idioms And Phrasal Verbs