Refers to a "consideration for sleepers" action whereby --- in order to briefly look at something from the doorway of a pitch-dark room in which you know that one or more other humans are seeking a little shut-eye --- you first open up your own eyelids extra-wide to allow yourself maximum visibility, and then perform a super-quick "on-off" action (one-half-second at the absolute maximum) with the room's light-switch, so that you are able to check on whatever you needed to know (such as that there is nothing on the floor between you and the sleeper's bed, and thus you can safely tiptoe forward in the dark and crawl in with the slumberer without tripping), but minimize the disturbance of the sleepy person(s) by not having the ceiling-lamp lit long enough for him to even be much aware of it.
Considerate dude who's staying overnight at his girlfriend's apartment: I always use the "single-strobe light-flick" prior to re-joining Tiffany in her bed after I visit the Little Boys' Room during the night, just to make sure that neither of her cats has decided to stretch itself out on the floor of the bedroom. It avoids any unexpected "yowls in the dark", plus Tiffany tells me that she seldom even notices my brief room-illuminations, so that's a good thing.
by QuacksO September 7, 2018