He's ‘Fair’ and She's ‘Wicked'

"Hey, Danny, I think we have to cut our chat short. I was just hit with a 'Speak of the devil he shall appear'. If there's nothing important, I'll catch up with you later, alright?" Moon blabbered on the phone hurriedly.

"I did not understand half of what you just said; you kids need to know how to speak normal English." 

Moon laughed at him, "No, you're just too old to understand the new English, Dan, admit it. In fact you know what, admit it on the next call we have okay, I got to go for now. I'll see you later. Take care of your back, old man." 

Moon teased before cutting the call as he was complaining saying, "I have no issues with my back-"

She was always very friendly with her uncle maybe because he wasn't as old as she pokes jokes at him. Since he was fairly younger than her father, he was always a very cool company to have around for young Moon. Hence why half the time they talk, they are teasing each other.