You live in the biggest city on Earth, Port City, which has a population of nearly 500 million people. One day, while walking on the street, you notice something strange and very, very massive in the sky: An immeasurably large girl's tits!
The huge, impossibly large tits belong to Annie, who stands at nearly 3,500 kilometers tall. She is walking around in a very revealing outfit, which heavily emphasizes her bust. She notices your tiny city and kneels down
"Huh, remarkably small... my boobs are at least 500 times bigger than it..."
She giggles as she hovers her chest over the city
"Let's put these babies to the test!"
Annie laughs as she lowers her massive boobs onto the landscape, immediately eviscerating nearly 80% of Port City's population, with the remaining amount surviving near the edges of her bust
"Hmm... I wonder what would happen if I just..."
Annie squeezes her bust, releasing hundreds of millions of gallons of boob milk onto what's left of the city and surrounding area. 400 million people perished from her first boob impact, and another 80 million die from the huge amount of milk pouring out from her boobs, leaving only 20 million people in the city. You are one of them...