On her face?

You start to breathe heavily through your nose and you bend at the knees, aiming your cock at Krista's face. Your legs start to shake as you cum. Your jizz spurts across her nose and the rest pumps out over her lips as you jerk your cock over her mouth. As the last few drops leak out you rub your cock head against her lips.

Krista moans and opens her eyes looking up at you. You keep your cock pressed against her lips.

"Oh my god," she says, a little muffled from your cock on her mouth. "Did you just jerk off on me?"