An "ashcan copy" is the entertainment industry equivalent of "calling dibs" on a franchise by slapping together a crappy, low budget production simply so they can prove they own the rights.
The practice of creating ashcan copies began in the Golden Age of comics, when publishers would slap together a few copies of a comic in order to retain rights to use characters, titles, etc. by proving they're doing something with it.
This proof of use has become increasingly valuable in Hollywood, where licenses are hoarded by big companies even if they don't actually intend to create a show based on the franchise.
Recently, a low budget TV adaptation of Robert Jordan's fantasy classic The Wheel Of Time aired late at night on FXX, which amounted to half an hour of awfulness hastily created to prove ownership of rights.
Here it is complete with commercials:
It's unclear when the first ashcan copy of a movie or TV show was made, but this practice dates back to at least 1966, when producer Bill Snyder teamed up with animation director Gene Deitch to secure the rights to J.R.R. Tolkien's The Hobbit: