Continuity mistake: After Gibby is kicked into the stack of boxes, he slumps to the floor and a large sleeping bag or pillow appears beside him only to disappear in the following scene. Then when he takes off his shirt, a yellow extension cord appears on top of the boxes.
Continuity mistake: An unconscious Nora falls to the floor, her head landing squarely in the center of a white tile. But in the subsequent closeup, her head is on a grey tile.
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