I have a problem that I haven't been able to find an amicable solution to so far. I really don't like being touched, to the point where if someone is touching me unexpectedly I get confusion rising to panic if they won't stop. Over the years I've learned to keep myself under control somewhat, and to stop myself from reflexively shoving people away or hitting them. It still causes intense discomfort and is thoroughly unpleasant if people touch me. Most people that know me well know this and avoid excessive touching due to that.
The problem is, many acquaintances (friends of friends or colleagues) don't take this seriously at all even after repeated explainations.
In fact, some of them make a joke of it "Heh he doesn't like to be touched lets group hug him from behind" needless to say, it always makes me uncomfortable and it's really stressful and tiring and also sometimes I can't help myself and shove people away forcefully.
I've tried explaining several times that I don't like to be touched and that it causes me great discomfort, but to very little effect. Many of my acquaintances just don't take it seriously.
Short of throwing them across the room or having a mental breakdown in front of them, how do I convince them it's serious and I actually really don't want to be touched and am not just saying that? Is there any specific way I can phrase that request to convey I'm dead serious?