"Go Daffy" is an informal expression that is used to describe someone who has lost control or become crazy. There are many synonyms for this particular phrase, including "go crazy," "lose it," "become unhinged," "lose your marbles," "flip out," and "go off the deep end." All of these phrases convey the same idea that someone has lost control of their emotions or behavior and is acting in an irrational or bizarre manner. It is important to note that while these phrases are used casually in conversation, mental health is a serious issue that should be addressed with care and sensitivity.