That's called something like Bribery

Last night's conversation between me and an 8-year old.

Miranda: No, I don't want to have a bath!

Me:  You have to have a bath before bed.  You've been out in the sun 2 days in a row and you didn't have one last night.

Miranda: I did so have a bath yesterday!

Me: No, you did not.  You were watching videos, remember?

Miranda: *pause* I still don't want to have one today.

Me: Do you want to go to Rachel's birthday party and sleep over this weekend?

Miranda: YES!

Me: If you don't have a bath tonight, you sure as hell are not going to that party.

Miranda: You can't do that.  That's called something like... bribery.  And that's not right.

Me:  It's not bribery.  I am not rewarding you for good behaviour.  I am giving you an ultimatum.  I will take something away if you don't do what I say.

I think she has been watching to much television.