Ignore them when they talk to you. They're just bullies and idiots. They're not even smart enough to come up with anything intelligent or witty to retort with, hence making fun of you going to a BBQ as if that's somehow unusual.
They're just looking to get a rise out of you.
Ignore what they say and don't respond to them.
If they're physically disturbing you in classes, speak to your teacher (or even send an e-mail) explaining what they're doing and how you can't focus on class because of them. It might be embarassing, but mention even that it's affecting you outside of school too, which it clearly is because it's gotten you upset enough to have to come and vent here.
If your teacher doesn't do anything then take it to your school counsellor, or even principal.
There's nothing wrong with reporting troublesome people/behaviour to someone higher up.
When you're an adult and in a workplace and someone is causing similar trouble, would you really act on advice to throw insults back at them or fight them? No, you'd lose your job too.
