Spoiler: they will not play actual skeletons.
Frequent co-stars Bill Hader and Kristen Wiig are attached to play estranged siblings--still very much alive and driven by muscle locomotion, not black magicks--in The Skeleton Twins, an indie comedy to be directed by True Adolescents' Craig Johnson from a script he co-wrote with Black Swan's Mark Heyman. In the film, the disappointingly flesh-covered twins coincidentally manage to cheat certain death on the same day, sending each on a soul-searching mission that reunites them with each other and their past loves, with Hader revisiting "his old flame Rich" and Wiig returning to her ex-husband Luke Wilson, who plays a "nature frat boy," which I assume means a hemp necklace and cargo shorts will be present. The Duplass brothers are executive producing with Jared Goldman. As for why the film is titled The Skeleton Twins when it so thoroughly lacks any sort of undead bone creatures, I don't know. Maybe that's the surname. Or New Line already registered Final Destination: Familial Dramedy.