flap

vt. 1. [obs.] To unload a DECtape (so it goes flap, flap, flap...). Old-time
hackers at MIT tell of the days when the disk was device 0 and DEC
microtapes were 1, 2,... and attempting to flap device 0 would instead start
a motor banging inside a cabinet near the disk. 2. By extension, to unload
any magnetic tape, even if it no longer actually had a flap.
(The term could also be applied to DEC's TK50 cartridge tape drive,
which was a spectacularly misengineered contraption making a loud flapping
sound, almost like an old reel-type lawnmower, in one of its many
tape-eating failure modes.