The phrase "goes loco" is a colloquial way of describing someone's wild, crazy or irrational behavior. There are many synonyms that can be used in place of "goes loco" to convey this meaning. Some examples include "loses it," "flips out," "gets insane," "goes berserk," "has a meltdown," or "goes off the deep end." These phrases are often used to describe unpredictable or erratic behavior, and can be used in many different contexts. Whether someone is experiencing anger, frustration, or excitement, there are many ways to describe their behavior using colorful language that accurately captures their emotional state.