get a chef knife case and load it with knives,
thats what i got,
ive had people try abuse me before, i just jump out with knives in hand and start yelling shit, looking like a psycho, and they always shit.
as for your girl, get her to buy some pepper spray, ive peppered sprayd the inside of a dickhead v8 owner that would not stop giving me shit, can guarantee their car will not be drivable for a couple of hours