Challenge him to a fight

"Well, you're a shameless brute, and I have little need for your kind," you sigh. "You're not the kind to negotiate with gold, so let's try steel. I challenge you, according to my knowledge of Orcish customs, to the ****."

"Ha! I'll happily tear your skull apart in the arena. When, then?"

"I'm already shit sick of the stench-ridden air here. Let's do it now. Hopefully, your replacement is your better."