An increasingly large number of people seem to think that 'it's just a joke' is a way to say, 'yes, I was deliberately hurting you, but I think your pain is funny so you're not allowed to get mad about it'.
Madness string 98328
Working in IT is a lot like being a doctor where the patients get mad at you for asking them to tell you their symptoms and sometimes the diagnosis is they didn't realize they need to blink once in a while or they forgot how to use one of their arms.