Between you, me, and the lamppost

What is Between you, me, and the lamppost?

Between you, me, and the lamppost definition and meaning on Dictionary terms:
in the space separating (two points, objects, etc.): between New York and Chicago.
intermediate to, in time, quantity, or degree: between twelve and one o’clock; between 50 and 60 apples; between pink and red.
linking; connecting: air service between cities.
in portions for each of (two people): splitting the profits between them.

among: sharing the responsibilities between the five of us.
by the dual or common action or participation of: Between us, we can finish the job in a couple of hours.
distinguishing one from the other: He couldn’t see the difference between good and bad.
in comparing: no preference between the two wines.
by the combined effect of.
existing confidentially for: We’ll keep this matter between the two of us.
involving; concerning: war between nations; choice between things.
being felt jointly or reciprocated by: the love between them.
by joint possession of: Between them they own most of this company.
Heraldry. in the midst of, so as to make a symmetrical composition: a cross argent between four bezants.

Usually betweens. a short needle with a rounded eye and a sharp point, used for fine hand stitchery in heavy fabric.

in the intervening space or time; in an intermediate position or relation: two windows with a door between; visits that were far between.