Used in casual settings among friends or family, not in formal situations.

Colloquial Usage

'Sack out' is a metaphorical expression and does not involve any actual sack.

Not Literal

Often suggests being very tired or worn out before sleeping.

Implies a short, sometimes unplanned stay, not a permanent living arrangement.

Suggests a casual and possibly improvised sleeping arrangement.

Recognize it as a part of American slang, comfortably used in US contexts.