It's not intelligence, it's difference. If you have something that significantly differentiates you from everyone else, even a single event, you are fucked...significantly. More or so, if you show a reaction to the ridicule. Even if no one really acknowledges it, there will be always be a few assholes waiting to bring it up. Some kids can suck it up for awhile, but it will get to them after awhile especially if they don't have any actual outlets. They may enjoy being alone, or not hanging around as many people but that will still pick people out. Especially body language.
They can pick on you for anything. From the type of pants you wear, the type of music you listen to, having a widows peak, farting in class, "looking like a certain presidential candidate", having a weird middle name which for some reason is apparently your first name, since social security says it is, but for some reason I was never told this and now from Middle school, to High School, to college, will have to be referred tom on attendance list and having to explain myself over and OVER AND OVER AND OVER AND FUCKING OVER AN-...they can pick on you for anything. But then it's all really about how they react to it...which for the most part, the one doing the bullying doesn't care, they just want to point and laugh since sarcasm and joking goes right over their head.
Now, time to be honest. As many have said in this thread, some people deserve to be ridiculed for their ridiculous actions. They may not necessarily be bad, or understand how people react to what they do. Some kids are too excited, act really strange, act smug etc, etc. Truthfully, though they mean no harm, need to be pulled back to reality and get a little kick. Eventually, they will calm down, will reconsider what they do, or simply be quiet and try to not to catch too much attention. There's just one problem: they never stop. Never. They never stop being ridiculed, being humiliated, even after they've learned their lesson. At least one asshole will constantly remind them of their failures, their problems, their flaws.
During elementary this can be pretty minimal and not too significant but still enough to be an issue. Around Middle School, kids tend to get a bit more vicious, don't give a fuck about anything, just want to be irritating. Now High school is truly the game changer. People are maturing, forgetting about past prejudices because they have their own shit to worry about. You have to go out of your way to truly get people to mess with you. If you have a past in any of these scenarios, than that will determine how people react.
TL

R It's all about behind different, how you act, a how you react, and the general mindset of everyone around you. A.K.A social skills. However, no matter how social or not, some people are gonna be pricks no matter what, whether they are smart, dumb, weird, etc, etc. If someone learns not to act a certain way and get people to mess with them, doesn't matter because someone will still mess with that person.