Reverse PMS
If a person who is usually mean the entire month, suddenly is nice for a few days and then goes back to being mean- they may have Reverse PMS.
Danny: "I was walking down the street and Brenda actually spoke and said hello to me. It sort of freaked me out."
John: "Don't worry, it is just Reverse PMS, she'll go back to being herself in just a few days."
John: "Don't worry, it is just Reverse PMS, she'll go back to being herself in just a few days."