It depends on what type of mad reaction you're looking for. you could;
1. Clench your fists and maybe stomp your foot if you're looking for an exaggerated, maybe even comical display of anger
2. turn away slightly and grab your head/hair in a slightly hysterical anger
3. Shake your fist at them
4. Cross your arms over your chest
Or some combination of those things, I hope that gives you some ideas!
