Free Wisp Tea

Head to the upstairs of the Farmhouse and interact with the static TV screen to change the channel until you get to a channel showing the twins, stare at the twins until they disappear off the screen, then, keep interacting with the TV until one of the twins is missing, head down to the cellar to find the ghost of the twin playing Tic Tac Toe, and approach her to get her to disappear.

Finally, stare at the TV until they both disappear, then, continue interacting with the TV to get to a channel where the twins are together, keep going until they are both missing, and then near the Power Generator, you'll find the two twins playing, which once approached, will drop you some loot, including a free Wisp Tea perk.