I think at this point, it would be the most effective to just completely ignore them. As long as they're going to get a "rise" out of you, they're probably going to continue. And that might even include reminding them that you don't like what they're doing. It's not that they don't know at this point what bothers you. They seem to just be waiting for you to complain just so they can make fun of you about it. Just ignore them completely and try to not let them see you upset. They should get bored of it soon enough.