We have very flexible working hours in our (rather small, i.e. everybody knows everybody) company. For that, I sometimes come late to work, say after 11 a.m., rarely after 12 or 1 p.m. Now some time ago my coworkers started to make jokes about this. Some examples: they say that I always come late; they say I behave like a university student; when they have lunch they ask me if I want to join for my breakfast; they pretend being overly surprised when I show up at 8 or 9 a.m. You get the point. I would say that I am a person with a lot of humor, but this behavior and the way they make these jokes is for some reason starting to reeeeally annoy me. Do you have any advice, how to counteract this - without changing my work hours?

To prevent possible questions that might come up: My working hours do not impact negatively on my work being done. When there is the need for me to come early, e.g. for a meeting, I am there. Everybody is satisfied with what I do. These coworkers are also not my superiors and not even in the same projects as I am. Also, my boss and the coworkers that are in my projects are ok with my working hours (and they also make no jokes...).