Cast a spell on him

"Sorry Harry, but the first time is the worst. The Body Hair Shaving Spell hurts less each time you use it, until you don't feel anything from it," she told him.

“What do you mean Body Hair Shaving Spell?” Harry asked, “Why would I have to keep using that spell?”

Rolling her eyes, Hermione told him, “I see there’s a lot I have to tech you Harry, but seriously, it’s fairly unsightly for a witch to be unshaven when they can help it.”

“It’s generally excused for witches who are new or haven’t gotten a wand yet, as well as those who didn’t have someone teaching them otherwise,” she finished.

Using one hand to block is penis still, Harry waved at his chest with the other contesting, “I still don’t know how you could consider me a witch since I don’t even have any boobs.”

Sighing, Hermione told him, “Harry, like I said earlier, I don’t know who’s been telling you those things, but you don’t have to worry about it, your boobs will be large enough in the end.”

“What are you talking about Hermione? How could my boobs get larger when I’m not a witch,” Harry asked her.

Point her wand at him she cast a spell on him, “Crescere Libris.”

“Woah!” Harry cried out as he felt his chest begin to squirm, before two tits began to form. His breasts swelled until he a had B-Cup sized chest.

“See,” Hermione pointed at him and commented smugly, “Now no one can say your not a witch.”

“W-what.. w-why.. how did you do that Hermione?!” Harry desperately asked.

Misunderstanding what he was asking she told him, “Sorry Harry, but you'd have to wait a year to use the spell again and it can only affect you three times during your life. Most witches wait until they seem to be finished growing to use it because it will guarantee you go up a cup size."

"Wait," Harry interrupted trying to get his thoughts together, "If most witches wait until they finish growing to use it, then why did you cast it on me?"

"Harry," Hermione tried to patiently tell him, "If you hadn't interrupted me, I would have told you that in Five Hundred and One Spells and Skills Every Witch Needs to Know, which is a required reading used to becoming a better witch, it says to use the spell if you don't have at least B-Cups, which are required for every witch to have as part of the curriculum."

“Wait wait wait,” Harry hurriedly said, “Why is having at least B-Cups required for part of the curriculum?”

“Hmm, that I don’t know, but it wasn’t a problem for me because I’m already at least a B-Cup,” Hermione responded, “Now, enough questions, it’s time to get dressed.”