It makes perfect sense
We had a new arrival to the neighborhood recently, a boy in the same age bracket as my 10-year old. I heard about him through the kid-grapevine, when my kids said they were going over to say hi.
Since then, he’s become part of the neighborhood pack of friends, one of the crew that gathers whenever there’s a break from the required of school and parents.
I met him for the first time yesterday. He and another friend had come over to collect my kids for some rip-sticking. As my youngest (who’s ten years old) was leaving, we did our secret handshake.
“What’s that?” the new boy asked.
“Secret handshake,” I said. “Gotta have one.”
“So we each know if the other has been replaced by an alien. An alien might be able to look like him, but he’d never know the secret handshake.”
He considered that for a moment, then nodded. “That makes sense.”