As a dad I would encourage the kid to stick up for himself if he seemed kind of timid, or at least trying to laugh it off and make friends of his/her own. Telling them to do this and having it done are different things though, especially when the bully uses his pack of friends to help. Some people are just genetically wired to be more timid and are going to have a harder time of things... that's life. It's not pretty, it's not fair, but it is what it is. You'll always have the quiet kid sitting in the corner by himself, while the pack makes fun and turns him into potentially another movie theater massacre waiting to happen. It takes the parent to notice and dedication on their part to instill self confidence in the child in order to help reverse this.