At the last second, Jack utters the wish, "I wish my mind isn't affected by my wish!"
Suddenly, everything goes back to 'normal' -- a bright, beautiful day at the beach. Everyone is wearing swimwear appropriate for their bodies, and it seems like everything is back to the way it was. As the dizziness fades, Jack looks down and sees that he still has breasts. Really nice ones -- medium sized and well-shaped, perky! He realizes he is slightly turned on looking down the front of his own swimsuit. But he doesn't develop an erection. He just feels his vagina 'soften' and 'moisten'.
This confirms in Jack's mind that the body-swap among everyone at the beach is complete. Nobody seems upset. Several people are looking around as if they're just not sure what's going on. They don't seem to notice that their bodies are different, but they seem a little disoriented -- as if their deepest subconscious mind is still fighting against accepting that their new body is their correct body.
Jack feels his female body responding sexually. "This is sooooo weird! I can't believe I'm in this body! I should change myself back before something worse happens!"