loco
adj. B2 Upper Intermediate US //ˈɫoʊkoʊ// UK //lˈəʊkəʊ// lo·co
adj. crazy or wild. You use this informal word to describe someone acting in a strange or silly way.
adj. mentally unstable or acting in a wild, irrational manner. Borrowed from Spanish; restricted to informal or colloquial registers.
The crowd went loco when the band started playing.
He must be loco if he thinks he can finish all that work in one hour.
The atmosphere in the stadium turned absolutely loco after the underdog team scored the winning goal in the final seconds of the match.
Usage
Often follows linking verbs like 'go' or 'be'.