When used in a colloquial context to 'go insane', 'go crazy', 'go mad', 'go nuts' and 'go ballistic', can describe irrational anger or losing control. "When I told her I crashed the car, she went ballistic." ('ballistics' refer to firearms or explosives) "If my father found out I like to smoke he would go nuts." If you 'go insane', 'go crazy' or 'go nuts', it can mean to lose control or submit to erratic behaviour. "When the President arrived his supporters went nuts. They screamed and chanted and held up banners." "When I get my holiday this month I'm going to go crazy. I'm going to go to an expensive hotel and go partying every night." "When I asked her to marry me she went insane, shouting and crying and screeching." As you can see from these examples the expressions can be used in a positive or negative context and are very colloquial. These expressions are best used with friends and avoided in formal conversations. In spoken English, the intonation used is very important to convey the appropriate meaning. If you say someone 'is mad' or that they 'are crazy' or 'insane', this has a very negative connotation and will be understood literally.