Hey buddy, I think you've got the wrong door, the leather club's two blocks down.
♥♥♥♥ You
Oh, ♥♥♥♥♂You leather man. Maybe you and I should settle it right here on the ring if you think your so tough.
Oh yea? I'll kick your ass!
Ha! Yeah right man. Let's go! Why don't you get out of that leather stuff? I'll strip down out of this and we'll settle it right here in the ring. What do you say?
Yeah, no problem buddy!
You got it. Get out of that uh, jabroni outfit.
Yeah, smart ass.
I'll show you who's the boss of this gym.

Firstly, Van entered the locker room of the gym to change up. Do people usually enter a gym in gym attire? No. There is a reason locker rooms exist. Mark didn't seem to understand this despite being the "boss" and told Van to go to the leather club. That is pretty ♥♥♥♥♥♥♥ rude. Van had just left that place. Obviously Van became aggravated by it and said "♥♥♥♥ you" which is totally understandable. Don't you get it? Leatherman likes to go to the gym after work, it's a way to release stress for him. It's really important for his day. He comes to the gym after a long 12 hour shift at the leatherclub, serving drinks to old men and getting slapped on the ass, he comes to the gym to cool off, get his mind off things and just lift some weights. He walks into the dressing room to get changed as he's still in his work attire, and some ♥♥♥♥♥♥♥ ♥♥♥♥♥♥♥ he's never seen before tells him to go to the leatherclub that he just came from. So he tells the ♥♥♥♥♥♥♥ off, to which the ♥♥♥♥♥♥♥ reacts violently enough to spark a fight. Not only that, the ♥♥♥♥♥♥♥ claims to be the "boss of this gym" which clearly isn't true since Leatherman is a long-time customer and knows the owner personally. My theory is that Billy is the true boss of the gym and Mark was just a phony. Even Billy says that Mark talks a lot of ♥♥♥♥ when they fought each other. And guess what, Billy won.

"... In the face of common dangers, in this winter of our hardship, let us remember these timeless words: ass we can." - Billy