Isn't it obvious?

In the style of someone who has faced requests like this on many occasions, Louise bends forward and clasps her knees, making her ass protrude behind her. She looks mournful, but not panicking.

I roll her skirt up till its around her waist like a belt then pull her shiny pantyhose and panties down to her knees. Again she doesn't seem shocked.

I hold onto her skirt-belt for balance, then push the index finger of my other hand at her anus firmly until it pops inside. This does seem to surprise her. Her eyes widen instantly, but she does not make a sound. Gently I work my finger around, loosening up the resistance of her sphincter, and gradually will my finger to slowly grow until after a minute it is seven inches long and as thick as Louise's forearm. I can see her wince a little. however, I continue to work it and make sure her ass is nice and wide before removing my finger and allowing it to shrink once more, admiring the gaping hole left behind, which I immediately fill with my cock.

I grab her by the hips and start buggering her with abandon, allowing her ass to swell as I do until when I eventually cum in her anus, her ass is bigger than Kim Kardashian's.

Afterwards, when I get dressed, she discovers her panties wont go back up over her ass, and her skirt wont come back down again either.

"Never mind, just take them off." I advise.

"o...ok", she says nervously and begins to strip, just leaving herself in the ridiculous blouse which is now tight on her large D cup tits. "I,...I thought you were going to spank me. I've never done that before" she mentions.

So that's why she seemed used to getting into the position! "Ah!" I say, slightly lost for words, and prepare for a bit of mind alteration.

"Its ok. Thanks. Its better than the spankings. I mean, I dont mind. You can spank me too. That is if you want to." she babbled nervously. "They teach us here that our husbands might want to do our asses too. We've got a class for it. I just havent done that one yet."

"Maybe later!" I laughed and gave her huge butt a friendly pat. I looked a little closer and could make out faded welts which looked as if she had taken beatings with something like a cane. What one earth kind of school was this?