She begs him to stop

Emily's tummy clenched with sudden anxiety at Mr. Jenkins statement. She'd never taken a cock in her ass, and had only teased herself there with a toy while she masturbated, not even inserting it. Despite how much she loved being dominated and fucked hard by him, she feared that she wouldn't be able to take him, that it would hurt too much and that she would disappoint him. And disappointing him might mean that he didn't tip her as generously, or that he wouldn't request her again. She didn't know which of those she feared worse.

All these thoughts ran through her head in less than a second as he manhandled her into position, his breathing hoarse with lust as he prepared to mount her. Biting her lip and staring back at him, she made her decision.

"Please don't Mr. Jenkins...Master....Please...I've never done that! I'm scared! You're so big, and I'm so tight! Please don't! Please Master! Please fuck my pussy instead! Fuck my slutty whore pussy! Please Master! Please! I'm begging you Master! Please don't fuck my ass!"