IWanna Stay with Spencer - S1-E5
Other mistake: The "Fan of Hammers" has all the hammers pointed the same way. But when the hammer goes into the wall, it goes in backwards. It is also there through all the rest of the shows and even in season two, where in "iKiss" it has a black handle. (00:02:35)
Answer: In direction translation it means 'Mischievous Spirit'. 'Hob' as in HobGoblin means clown or prankster, and 'Knocker' was an old age term for Poltergeists in mines. Miners would often complain of hearing knocking sounds down mines when there was no-one else down there, hence 'Knocker'. It's not a regular English expression though.
GalahadFairlight