I agree with Macaco's answer. Just wanted to chime in with my own thoughts as well.
There are generally five ways to use a nunchuck:
For intimidation. Twirling any weapon around is scary to your opponent.
Flailing it around. The end of the nunchuck is used to strike your
Using it as a solid stick instead of a flexible weapon. Usually you grab both ...
Just to get the obvious out of the way, your best defense against most attacks is to run and get help, maybe preceding it by delaying the other person by throwing something at them before running.
Outside of that, a lot of the defense will depend on the flexible nature of the nunchaku. I'd say that your first priority is to have something other than your ...