I grew up with a brother that made it a goal of his to constantly rip on me, in front of friends, family, my friends and everyone at every given opportunity. The hard part is their lame answer to your retorts are alwasy "you have no sense of humor" and "you're too serious" My solution, at whatever point they don't get your comments to their jokes, just leave the scene, if you can. Even if just to another room or part of the house/place. First thing it does, you've already voiced your complaint, it didn't work. This gets you out of the situation to re-coup. Second, it brings attention to how their behavior is not going to be tolerated. It makes it clear under no uncertain terms that you will not be there for them to use as their butt of jokes. Thirdly, it stops them, since all their focus was on you at the time, you being gone will leave them no alternative but to refocus their attention. At the same time, it breaks the cycle and could possibly make them think about what they were doing. Done in a consistent manner, I believe it can actually change things for you. This is all just my theoretical idea but I think there's some truth in it and hope it helps.