“Well,” said Frobisher, “I probably should change back from being a penguin.”
“You don't have to,” the Doctor said quickly.
Frobisher shook his head. “Nah, Doc, I think I probably should. Cloacas can make things awkward when the other person doesn't have one.”
The Doctor nodded sagely. “Hence why you became an penguin for Francine.”
“Something like that,” said Frobisher, who was melting into his default form: a pale yellow humanoid form, quite short, his face featureless. Unlike his usual appearance, this version of him wore glasses. He was still naked, though.
The Doctor glanced between his legs. “Frobisher...?”
“You don't seem to have any genatalia.”
Frobisher laughed. “I'm a Whifferdill, Doc. I can grow whatever parts you like. Lemme show you.”
“Hmm,” said the Doctor, kneeling down to better inspect Frobisher's newly grown cock and balls. “Yes, I can see where that would be an advantage. Do you mind if I...?”
“Huh? No, go right ahead, Doc.”
“Thank you, Frobisher.”
Oh yeah, thought Frobisher, as the Doctor started humming around his cock. He'd figured the Doctor would be good with his mouth. Maybe next they could do it with Frobisher taking the Doctor's shape. He was pretty sure the Doctor would get off on fucking himself–and if not, Frobisher would definitely get off on fucking the Doctor as the Doctor. And then afterwards, he'd have the TARDIS make a fish for him in the bath and have a nice post-coital hunt.
Yeah, life was good.