a fly on the wall
fly on the wall
One who is able to observe something closely but invisibly and without interfering in the situation. I would love to be a fly on the wall in John's house when he finds out his wife bought a new car without telling him.
Farlex Dictionary of Idioms. © 2015 Farlex, Inc, all rights reserved.
a fly on the wall
COMMON If you would like to be a fly on the wall when a particular thing happens, you would like to secretly hear what is said or see what happens. I'd love to be a fly on the wall at their team meetings. What I'd give to be a fly on the wall when Draper finds out what's happened to his precious cargo! Note: You can use fly-on-the-wall to describe something such as a documentary film (= film about real people and events), where the makers of the film record everything that happens. For six months, a BBC film crew worked on a fly-on-the-wall documentary about their forthcoming marriage.
Collins COBUILD Idioms Dictionary, 3rd ed. © HarperCollins Publishers 2012
a fly on the wall
an unnoticed observer of a particular situation.This expression is often used as an adjective, as in a fly-on-the-wall documentary , where it refers to a film-making technique in which events are merely observed and presented realistically with minimum interference, rather than acted out under direction.
Farlex Partner Idioms Dictionary © Farlex 2017
a fly on the ˈwall
a person who watches others without being noticed: I’d love to be a fly on the wall when the committee is discussing the report I wrote! ♢ fly-on-the-wall documentaries (= in which people are filmed going about their normal lives as if the camera were not there)Farlex Partner Idioms Dictionary © Farlex 2017