I did something like this once! I was BBSing and my CGA monitor's vertical coil died. So I blew through my lips to make a 'raspberry' sound which vibrated my eyes and allowed me to read what was being displayed on the single scan line.
Much less clever, but I had a microwave with far too opaque a grid to look through. By shaking my head left and right, it would sort of disappear though. The funny thing is how automatic these human things are. I didn't notice I was doing it until someone asked me why I was shaking my head at the microwave.
Thanks for sharing this story, I laughed out loud trying to visualize the notion of someone staring at a semingly blank screen doing that in order to read the "secret text". Brilliant.
OP was reading text on an old Cathode Ray Tube monitor. It broke such that, instead of being spread throughout the screen, all of it was squished vertically into a single horizontal line. However, different parts of the line are written at different times, so if you vibrate your head, different parts will land at different parts of your eye.
OP is probably using something like a retroencabulator where rather than the power being generated by the relative motion of conductors and fluxes, it’s produced by the modial interaction of magneto-reluctance and capacitive diractance. The original machine had a base plate of prefabulated amulite, surmounted by a malleable logarithmic casing in such a way that the two spurving bearings were in a direct line with the panametric fan. Thus no pixel return springs are necessary in this configuration.
Displayed would have been a static unmoving screen of text (a typical BBS display), so the unsynced perturbations of haphazard raspberry motion should create enough randomly coincident content time-slices to form a complete image.
EDIT to add: someone please make an emulation of this, with a slider to control the raspberry's pitch.