I'm going to diss my friend at the bar
Why would you diss your friend?
Yes, I hate him for being boring.
You shouldn't put down your friends in public. Maybe you can talk to your friend about how they can be more fun? It might be less hurtful for him than insulting him publicly which will make him feel worse.
I'm going to give him a chance.
I'm really glad you're gonna give him another shot. I hope it works out.