fly on the wall
An unseen observer or listener, as in I wish I could be a fly on the wall when she tells him she's pregnant. [Mid-1900s]
HEED THE VOX POPULI, AND TAKE THIS WORD OF THE DAY QUIZ!
Words nearby fly on the wall
Example sentences from the Web for fly on the wall
Since 1984, Newsweek has made a cottage industry out of its fly-on-the-wall post-election coverage of presidential campaigns.
He could play the fly-on-the-wall in Louis the Goon's life as long as he wanted.