Surprise her from behind

"I think I can come up with something," you assure her softly, patting her flank so that her big thighs and bottom jiggle. "Roll over for me."

She nods with a look of mixed confusion and excitement, shifting to all fours as if she were a natural cow. Her tail brushes aside, resting on one of her cheeks as she spreads her legs to expose her swollen and dripping sex to you. You rub at it gently, letting your longer fingers brush against her udders. Her low moan is a big turnon, but you don't enter from there. You carefully rub and spread on off her black and white ass cheeks and press your head against her puckered rear.

"MOOO-OHHH!" She gives a lusty gasp in surprise, feeling you slowly push into her tighter hole.

"Still haven't tried that out yet," you pant a bit, seeing her ears flick in excitement as she arches her back. You reach one hand around, barely able to get around her big belly to rub at her breasts. "You like it?"

"Don't stop," is all she managed to utter, as you start to thrust into her more steadily. She seems to ease up a bit, but grows no less horny as you let her big soft bottom wobble against your hips. Her thick fingers grab at the sheets below, mouth hanging open wide enough that you can see it as she rests her cheek on the bed. "Yes... yes... master, just like that. Touch my pussy while you take my bottom!"

You chuckle at her cute term for her ass, but keep your fingers spreading her pussy lips, dripping and sticky with her arousal as you reach in and find her fat, swollen clit, pinching gently at it as she wails like a pleading child for more.