Only if it makes their head explode as you suggest.
Which we really only have your word for.
If I can hit a guy in the brachial plexus I will. It is a legal target.
Just for you science boffins behind the ear might be the Vegas nerve. Probably much safer.
So let me get this straight.....at the gymn while training you would target your training partner's Brachial Plexus? Why?