There's a forum topic on the IMDB page for "Movie 43" titled "What is this exactly?" The red band trailer doesn't really offer any answers, but it's awfully damn funny.
It seems like almost everyone in Hollywood makes an appearance in this raunchy anthology film, weaving in and out of various outrageous plots and situations and apparently told to be as offensive as possible at all times.
There are more laughs in this most definitely NSFW trailer than there are in some feature-length comedies, with the highlights being Gerard Butler as an enraged kidnapped leprechaun (yep), Emma Stone discussing STDs with Kieran Culkin, Terrence Howard giving a rather rousing pep talk to his basketball team and ... wait a minute, how did someone convince even Hugh Jackman, Richard Gere and Kate Winslet to be in this thing?
"Movie 43" makes for the collected work of no less than 11 directors, including Elizabeth Banks (?), Brett Ratner, Peter Farrelly and future "Guardians of the Galaxy" helmer James Gunn. It's most definitely a proud addition to any resume.
Check out the very, very NSFW trailer below, which premiered on Comedy Central. "Movie 43" opens Jan. 25, 2013.