After getting a kiss from your girlfriend, you gazed back at the moon, which caused you to shake a bit, starting with a bulge increasing its size in your pants, which made you sweat, and take off your t-shirt from the heat building up in you. Finally your penis breaks through the pants, while turning bright pink, and getting longer.
Your girlfriend looked at the back of you, seeing your pants rip, while your butt expanded, and a long tail sprouted with some hairlines that matched the same color as your hair covered it while you tried to get up. White fur covered your body, while your arms, and legs extended, and the nails of both your fingers, and toes hardened while more of your body got bigger. You couldn't take it, as your massive erection made it harder for you to get up off the ground while you were on all-fours.