Jack realizes what a mess he's made.
The 'girls' turned 'hunks' are still wearing their female swimsuits, and vice-versa.
"I wish everyone's body transformation is completed, including genitals and including the right swimsuit for their body!"
That seemed to fix everything for the most part - everyone was now correctly dressed for their 'equipment', except now people were starting to realize their bodies had been swapped, and some started to panic.
Quick! "I wish everyone's mind accepted the transformation as if that was their birth-gender! And I wish that their families and everyone only remembered them as being their new gender." This wish started to take effect, but it seemed to require a lot of space-time changes, so it was occurring slowly over the course of several minutes.
Jack suddenly felt very sick to his stomach and a wave of sweat swept through him. He felt faint and sat on the sand for a minute. Then he realized for the first time that he was wearing a women's swimsuit. It dawned on him that his crotch was flat and smooth and his breasts were being supported by the straps of his swimsuit. "Oh, no! I forgot to exempt myself from the wish!!!"
He could 'feel' his testicles -- already drawn up into his abdomen -- flip into ovaries. He could feel all of the testosterone transformed into estrogen and instantly he felt vert 'female'.
At that moment, he realized that his wish, if taken to completion, would erase his memory of his manhood -- because it would change everyone's memory, including his own, to believe his new gender was his birth gender.
As the changes continue to ripple across the beach and across the memories of every friend and family member of those at the beach, Jack realizes he only has a few seconds left to make a wish to save himself...to save his manhood and his identity...