It's wrong to not do what your employer asks.
Dennis is stocking cereal at the grocery store and his manager tells him he has to finish stocking it before he goes on lunch break.
Dennis wants to eat his lunch.
Dennis finishes stocking the cereal and then goes to the lunch room to eat.
Dennis goes to the lunch room as soon as his manager is out of sight, without finishing stocking the cereal.
Dennis' manager finds Dennis in the lunch room, thanks him for stocking the cereal, and joins him for lunch.
Dennis' manager finds Dennis in the lunch room and yells at him for not doing his job.