[BBB]

Okay. I'm used to prompts requiring a ton of trial and error, but here's an attempt.

A happy slender small-breasted young woman in a scoop neck crop top sits at the kitchen table with some party supplies. She picks up an empty latex balloon, holds it to her mouth, and blows two breaths. As she exhales, the balloon inflates to full size. Then she struggles to blow more air into the balloon. Then she looks very surprised as the balloon deflates while at the same time, her bust dramatically expands, becoming too big for her top. She looks down at her chest, shocked.