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!