a fly on the wall

a fly on the wall

(spoken)
someone who can secretly see and hear what happens I would love to be a fly on the wall at that meeting.
See also: fly, wall

a fly on the wall

if you say you would like to be a fly on the wall in a certain situation, you mean that you would like to be there secretly to see and hear what happens I'd give anything to be a fly on the wall when she tells him.
See also: fly, wall