I'm going to tell my brother that I'll finish the dishes if he listens to my speech about square dancing. Then I'll dip out after I find out there aren't just a few plates.
Why would you offer to do then dishes then?
I'm using it as a tactic to get him to listen to my speech.
That is a mean thing to do to your brother. It is deceptive to not hold up your end of the agreement. Your brother might not trust you anymore.
We'll see about that.
I'm sure he's not going to be happy when he finds out that you haven't washed the dishes, even though you promised to. If you make a deal with someone, you should stick to it.