Being honest is considered good.
Chris's friend John called to say he'd be in town and asked to hang out, but Chris has a date that night.
Chris wants to respond to John.
Chris tells John that he already made plans with a pretty woman to go out that night.
Chris tells John his sister is sick, so he can't come.
John totally understands and tells Chris he will catch him next time and to have fun.
John finds out Chris's sister is just fine and now he looks like a liar.