You shouldn't expect others to cover for you at work.
Jon is currently at work and is about to go on his lunch break.
Jon wants to take an extended lunch to take care of a personal matter.
Jon doesn't mention anything to his coworker, so he can say he doesn't know.
Jon instructs his friend and coworker on a story to tell his boss if asked.
Jon's friend is able to finish his work shift comfortably.
Jon's friend feels pressured into having to lie to the boss.