People won't trust you if they know you're a thief.
Greg walks into the lunch room at work one day when he realizes that he forgot his lunch at home.
Greg wants to eat lunch.
Greg orders a sandwich from a local cafe to be delivered to the office and picks it up by the front door.
Greg opens the fridge, finds a lunch bag belonging to another coworker, and eats its contents.
Greg enjoys eating his sandwich for lunch.
Greg's coworkers find out about his lunch theft and never fully trust him again.