"Goes mat" is a common idiom that refers to someone who loses their temper or becomes angry. There are several synonyms that can be used instead of this phrase, depending on the context and level of aggression. Some possible synonyms for "goes mat" include "flips out," "loses it," "flies off the handle," "blows a fuse," "has a meltdown," "goes ballistic," and "goes off the deep end." While each of these phrases conveys a similar meaning, they may be used in different situations or to emphasize different levels of anger. It's important to choose the right synonym to accurately convey the intended message.