Put together a lot of images with hard deepthroat action. A bit of frowning, a bit of struggling, you see it hits the back of her throat.

trained on realistic images.

Strength: 0.7-1.0

Sadly there is no cum in the trainings pics, so you will need a lora for this. maybe use my "sloppy enhancement lora"

Proompting:
a photograph depicting a sexual act between a girl and a man. image shows one girl and one man. the girl is performing oral sex on the man. the man's lower torso is visible, but his face is out of the frame. the girl has his large, erect, penis in her mouth. his left hand is gripping her hair.  she is gagging on the penis. extreme rough deepthroat and oral sex. 

she is on her knees

Describing expressions works well: surprised, disgusted, wide eyes, etc.