The line between gross-out humor that’s inspired and the kind that’s witless is fine indeed, and “Movie 43” obliterates it with poop and movie stars.

What are the likes of Kate Winslet, Hugh Jackman, Halle Berry, Richard Gere, Emma Stone, and Uma Thurman doing in this cheerfully disgusting, regrettably hit-and-miss sketch-comedy omnibus? Only their agents know for sure. Maybe they owed a favor to Peter Farrelly, the film’s producer and co-director, one half of the Farrelly brothers (“There’s Something About Mary”), and a man whose life philosophy could be summed up as: The more bodily fluids, the better.