Peter had changed into a twink because of the new "ability" that Sean had programmed into Dan. Now, whenever a guy insulted Dan's new homosexuality, the guy who made the insult would become gay, similar to Dan himself, in the way he looked and the way he talked and moved. That's what happened to Peter.
Sean followed the two gay boys from a distance, as they headed to the hair salon, a place that neither boy had any interest in going to before their transformations. But now, they just couldn't wait.
On the way there, Sean had the opportunity to see Dan's "twink infection" work its magic again. He hid behind a large tree and watched.