Writing in Dialogue

"Hey Binky, what are you up to today?" asked Pip in a voice that suggested she was up to something yet again.
"Um...Well I havn't decided if I am yet, it depends on what you're planning", replied Binky looking slightly worried.
"OK, listen up!"
"Riiiiight", Binky paused "Carry on."
"Well I was thinking..................................................We could go on a waterslide in the other Llama's paddock!"
"Have you thought of how we are going to make it exactly?"
"No"
"Have you thought of how we're going to get down there without the grumpy old farmer seeing us because you know what happens if he does?"
"No"
"Have you thought about that we have no water to do it with?"
"No"
"Well that was kinda stupid then wasn't it?"
"Yup"
"OK, I'll help you make the waterslide if you promise me that I don't have to go down it. Deal?"
"No"
"Oh Pip, stop being so difficult for once!"
"Fine, if you help, you don't have to go down", Pip huffed