I don't like clowns, I find them incredibly creepy, but I don't have a phobia about them. I don't know much about phobias at all, really. I guess my best advice is to just respect his feelings and support him. If it is really an issue where he can't even speak about it, perhaps therapy is in order.
He doesn't mind talking about it in a general sense but not about how his phobia came about. I think he is slightly embarrassed about it, so I didn't pursue the issue. I'd like to hear from others, though.
I have a friend with fear of clowns and people wearing big unique costumes for festivals in general. She finds them very creepy and can't look at them properly. We've been trying to find the reason, whether it's childhood trauma or anything else, but we can't find anything. Is that even possible?
Yes, it is possible for people to have all sorts of phobias. Usually they arise from unpleasant past events that were connected to the object of fear. It's strange that your friend doesn't remember the cause of her phobia.