Jon looked down at himself and saw that he was a girl! It must have been a gender swap that happened.
"Oh my god, what happened to me?!" he heard a man yell. He looked up and saw a man in a shirt and tie who looked like a male version of his mom. His mother worked in an office, so she wore office attire. This was the male equivalent.
"Mom, listen to me. It's okay," Jon said. It was so weird hearing a girl's voice when he was speaking.
"What's going on?" Jane asked, settling down, but still clearly freaked out.
Jon didn't bother giving her (or was it him now?) an explanation. He (or rather she) reached out and touched Jane's new male hand and said "Swap."