Nuh doesn't have what?

You sit between the girls and knead their grebnaks like dough.

"Saffire," Blackfire whispers. "Not in front of your sister!"

"Oh, right. Flashfire, turn around!"

"Why should I?" she asks. "Maybe you should just go to sleep and leave their grebnaks alone!"

"Like that's going to happen!" you say as you continue to knead the grebnaks.

You recline back and bring the girls' chests closer to your face. That is when you notice another thing about Nuh.

"You don't have k'nipkorfs?" you blurt out.

"What?" Nuh is confused. "What are 'k'nipkorfs'?!"

Blackfire also notices and smooths her hands over Nuh's grebnaks.

"She doesn't!" she exclaims. "They're completely smooth!" (NOTE: that is a made up Tamaranian word for nipples)

"Oh," Nuh says, understanding. "You mean those!" She points to Blackfire's k'nipkorfs. "What are they for?"

"Well, y'see, Nuh," you begin. "humanoid species with mouths also have k'nipkorfs. Baby humanoids extract milk from the grebnaks VIA the k'nipkorfs the same way baby blogorg cows extract milk from the udders of their mothers."

"Oh..." Nuh says, her eyes wide with learning. "Since my species feed off of body heat, our grebnaks act as large heating pads for our young."

"So the large size is needed to properly feed your children heat," Blackfire paraphrases.

"Exactly!"

"Wow, we all learned something about grebnaks tonight," you say.

A second or two of silence passes, then you pull the girls in close, smooshing your face into their chests.

"Saffire~!" the girls giggle.

"Pervert!" Flashfire says as she goes to the far side of the bed and lies down. "Let's just go to sleep already!"

"Fine, party-pooper!" you say as you lie down.

Nuh and Blackfire pull their shirts back down, and settle in, pressing their grebnaks close against your body. Slowly but surely, the four of you fall asleep.