Piper has a healthy disregard for most conventions. Like spelling. And pronunciation.
There is the Piper way of saying something and that’s it. You can correct her all you want. Go ahead. Waste your breath.
“Piper, it’s DARTH Vader. Not DARK Vader,” Daddy said last night as he was putting her to bed.
“That’s what I said. DARK Vader. Cuz his helmet’s black.”
“No, DARTH. With a TH.”
“Uh huh. Same thing.”
On Valentine’s Day Nana sent a care package. Piper wished us all a Happy VALENTIMES Day as she opened the box. As in, it’s TIME for Valentines.
Piper unwrapped her present and shouted, “Look! I got PELZ!”
“Those are PEZ, Piper,” Sissy corrected.
“I just love PELZ,” Piper said.
“PEZ. You love PEZ.”
“Yep. I love them both.”
piperism 
She’s right. It totally is Dark Vader. I said that when I was seven and I stand by it now at 29 (the 30s being the new 20s).
You’re right. Dark Vader makes so much more sense. It was probably just one of George Lucas’ spelling errors. Geez.