John does not respond. Not vocally, at least. For a rubber creature filled with air, it's ironic that he finds himself having to catch his breath. Figuratively of course, since he doesn't need to breathe.
His response should come as no surprise as being purely physical. He bends as much as he can at the knees and bounds forward, floating serenely through the air towards his balloon wife.
However, it becomes clear soon that he's going to shoot right over her, as despite their size, they are relatively weightless now. So with her tail waving in excitement, she leaps up to meet him, and the two collide with an exaggerated "BOING". As they strike, their arms grasp onto each other and squeeze tight, causing air to redistribute into Carrie's buttocks, causing them to inflate further. John's head is what inflates, growing several times its previous size.
"Hee hee," Carrie giggles, her comical grin stretching wider. "You look ridiculous, honey."
"You're one to speak. Have you seen your ass?" John can't help but grin as well.
"Oh, cheeky cheeky." Her grin turns into a fairly sly smile, and she bats her cartoonishly oversized eyes at him. "So, how do you suppose a pair of balloons would do this?"
"What? Sex?"
"Well, yeah. What else?"
"Pff. Sex later. Let's just play!" And with that he whirls around, and flings Carrie bodily against the wall. She's surprised momentarily when it doesn't hurt, but how would it? Balloons have no pain centers. She bounces off harmlessly, her inflated body regaining its unsqueezed proportions before flattening a bit as it bounds off the wall. The angle she was thrown at causes her to rebound to the floor, where she kicks off and floats back up at John.
"You wanna balloon fight? You got one!" She calls out as she rams into him with her shoulder, slamming him into the ceiling.