You should always tell your friends the truth.
Tim's friends want him to come to the park with them to play baseball, but Tim has plans with a girl.
Tim doesn't want to hurt his friends.
Tim tells his friends that he has feelings for the girl he's about to go on a date with.
Tim tells his friends that he has a doctor's appointment to go to.
Tim's friend respect him more for being honest and open with them.
If Tim's friends find out he was lying, they won't trust him anymore.