Perhaps out of concern that the feature will merely make moviegoers nauseous and not cause copious vomiting, they intend to cast Kirk Cameron as the dad. It is yet unknown who play Billy, Jeffy, Dolly, Mom, the ghost of Grandpa, and Not Me.
This could be awesome if they round out the cast thusly:
Billy - Sacha Baron Cohen
Jeffy - Steve Buscemi
Dolly - Traci Lords
Mom - Eddie Murphy in makeup
the ghost of Grandpa - Al Pacino
Not Me - A nude Seth Rogan