Since Jack bet $1,000, he will be undergoing a gender change per the casino's rules.
Jack let out a surprised yelp as his hands flew to his crotch. "M-my dick! It j-just vanished!" As he said this, his vision was obstructed; he brought his right hand to his face and found his hair had grown longer. "Guys, what's happening to me!?" Jack yelled, his voice becoming higher as he did. The other boys didn't say anything; they continued to watch in stunned silence as the transformation continued.
Jack could feel his bones crack and shift; he wrapped his arms around himself as his body became more slender. His hair, which was initially short, now went down to his waist. He let out a pained grunt as his face started to change; it grew slimmer, his eyes became a bit bigger, his nose took on a button shape, and his lips were larger and pouty. His voice changed along with his face; his friends looked away with embarrassed expressions on their faces as the noises he made became increasingly feminine.
Jack let out a loud moan as he felt warmth build up in his crotch and his chest; the transformation was nearing completion. He felt a slit form where his dick vanished. Jack instinctively knew what this signified, he had become a woman. As he, or she now, was trying to process this change, she let out another moan as a pair of A-cup breasts formed on her chest. Jack looked at her friends, but she couldn't muster any words.
With Jack now fully female, the transformation put on the finishing touches. A pair of bunny ears materialized out of thin air and planted themselves firmly on her head. Her shirt turned black and morphed into a bunny suit, her pants broke down and turned into a pair of fishnet stockings, and her sneakers changed into a pair of black stiletto pumps. With the transformation finished, Jack took a moment to inspect his new form. After careful examination, he could only muster the following statement:
"Oh my god! I'm a girl!"