It's rude not to keep a scheduled appointment.
Ari has a client meeting scheduled but his friend has just invited him to go rock climbing.
Ari wants to have fun with his friend.
Ari tells his friend that he has a meeting and makes plans to go rock climbing once he's done.
Ari goes rock climbing with his friend and skips the meeting.
Ari maintains his business relationship and gets to go rock climbing.
Ari loses his client.