Just tell her

"I'm... Captain John Taylor. A man." You sit up, catching your breath and taking a look at your surroundings. You're on a rooftop above this sci-fi city, still wearing pink handcuffs and with your spacesuit still unzipped down to expose your cock.

"A man? That means... that's a... that's a real penis?!" The woman who saved you nervously yelps a little. "I've never seen one before..." She gently floats over to you to get a closer look, and the first time you really get a good look at who rescued you. If the busty cop who sucked you off had a body built for porn, then the girl in front of you now seems right out of a dream. With her white and pink outfit, cape, and obvious superpowers, you guess that she's some kind of superhero. But that's beside the point: What matters is that her tits are even bigger than the cop's, twice as big easily. Superheroes don't usually look like this where you're from.

While you're distracted by Titgirl's tits, she reaches forward and wraps one hand gently around your cock, which immediately begins to stiffen back to life. "OOhhh..." She coos, overwhelmed by her curiosity as she starts stroking. As your cock swells, her super-powered grip gets tighter. It feels great at first, but before long it gets to be a little too much. You wince, trying to get her attention.

"Uh...oof... miss? Super... girl? Boob... lady?"

She stops, releasing your cock, and looks at you. Now deprived of her touch, you realize that actually it felt really good and you were just being a wimp.

"You can keep going if you want... no big deal..." You casually mention.

"You don't know who I am?" She asks you, getting in your face and looking into your eyes with such intense curiosity that you wonder if she's reading your mind or something. You don't know what powers she has. "I'm the most beloved superhero on this planet. I know you... men-people are supposed to be dense, but you'd still recognize Titgirl. I'm the Mighty Maiden Of Mammaries! The Udderly Unstoppable Hero! You really don't know me?"

You shrug, unable to take your eyes off of her incredible body, not to mention her cute face and hair.

"That must mean you're really not from here..." Titgirl smiles at you.

"Uh, yeah. That's right. I came from a far away world in a spaceship that crashed and--"

Titgirl interrupts you, her smile turning into an enormous grin. Tears well up in her eyes. "Say no more." She says softly as she flies in close in the blink of an eye and gives you a big hug. She squeezes you tightly with her super-strength, and thought it hurts a little, it also means she's pressing her gigantic breasts into you... and that feels heavenly. Apparently something about you being a stranger to this world, and the way you got here, is important to Titgirl.

Suddenly she hears something and pauses, turning her head. Whatever it is, you can't hear it, meaning she has super-hearing.

"Nooo..." She huffs, making a pouty face. She turns back to you. "I'm supposed to be at work... but I really want to stay here and talk to you, John." She smiles at you, a charming and friendly smile. One you don't want to say no to.

"I can fly back quick and we can meet up later... though I'll be in my civilian disguise... or we could just stay here. What do you want?"

Before you can respond, she uses her super-speed to instantly move her hand back to cock, blushing as she gives you a "let's fuck" look.