The menacing grin that comes with the killing Truth or Dare force is nicknamed the Willem Dafoe grin, and is in part inspired by his menacing smile and the facial disfigurement of the Gustavo Smile.
Tyler Posey and Lucy Hale's faces did not need much computer tweaking to create the smiles, Wadlow commenting that augmentation was only at 5% for the two of them.
Tyler Posey was found to be able to do most of the wide facial grin (without need of CGI) which he learned to do for his role in Teen Wolf (2011).
Jeff Wadlow pitched nothing but the title and opening sequence to Jason Blum to get him to sign on to the film.
The game Truth or Dare has existed by record for centuries, with earliest history as 1712 suggesting origin in being a Christmas questions and commands game.