65+ years ago... my mentor used to 'yank my chain' when getting ready to make a photograph. The 8x10 camera would be set up... the dark-cloth placed over the rear standard... lens adjusted for focus... set the required 'swing and/or tilt would be set... t
Then... out of my area of vision while I got to 'check' the GG once more... with a small folding loup.. ready to agree that everything was 'good to go'... he would take a 'sneaky' light meter reading... quickly and quietly return the meter to his jacket pocket... fuss about looking around a little... checking the 'cloud cover' and light 'intensity and direction'... he'd 'hum and haw' a little... then stick his finger in his mouth then 'hold it' pointing upwards and then deliberately state "out loud" that the correct exposure was going to be.. set the iris and shutter speed to that which he had already read off the light meter.
Dammit!!!!!... It only took me a couple of years to 'catch him out'.... and that was 'by mistake'.