This one is tricky. In order to get this achievements you need to have all jarred brains gathered and restored. After you get Mr. Pokeylope, instead of doing the mission, just go to the elevator down instead, and back on to the main island. Pickup Mr. Pokeylope in your hand and show it to everyone around the camp.
Quick list of kids and locations:
Kids cabin area: JT, Chops, Dogen, (they are outside standing), Kitty, Franke (inside the girls' house), Bobby and Chloe (all the way up, in the Coach's radio room).
Main lodge: Nils, Elka (on the patio outside of the lodge), Phoebe, Quentin, Vernon (inside the lodge), Maloof (in the parking lot, standing next to Mikhail who you can skip as he has nothing to say about it. Punch the car for extra fun if you haven't already).
Reception area: Clem, Crystal (cheering for Janitor on a terrace of a shed, also you can show it to Cruller too)
Lake: Elton, Milka (on the bridge).
Also, this achievement is great to combine with "Self Aware" achievement, which you can get by using clairvoyance power on everyone you visit. You don't actually have to position self to "see how they see you", but you might want to for some fun.
I hope this help. Cheers.