Flap

vt. 1. 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 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.

See also macrotape.

Modern cartridge tapes no longer actually flap, but the usage has remained.