HOLLA ON THE GO: Turned down harasser, threatened with violence

I was shopping by myself at this gas station, when a strange man came up and demanded I smile at him. I said “no, I don’t smile on command.”
He muttered curses, called me “reta**ed,” then said “how’d you like me to come kick your ass?”
I replied “How’d you like me to call the police and have you arrested?” He was increasingly agitated as I was trying to pay and leave. And the employees did nothing to help me.