Challenging someone to a fight

I have a relation who is the biggest bona quibus fruimus I've ever known. I wont go into details, but I can pretty much promise you, you'd feel as I do if it were you.


I'd like to get him in the ring, to avoid legal implications and to stay on the right side of the law. If he refuses my challenge, I'll have the satisfaction at least of reminding him on a regular basis that he's a coward.

Wondering if anyone has been in this situation, and if/how they managed to get the person concerned in the ring?