If they feel toxic to you and others then they are toxic. Many people are toxic without being aware of it, so when they say they are joking they could be telling the truth, or what they feel is the truth. Unconscious toxic behaviors are learned responses to stimuli, brought on by growing up in a toxic environment. Of course, they could also just be jerks and know perfectly well they are jerks. Either way, they should be called on this behavior and avoided if they make no attempt to change.