Friends with Benefits
I don't describe movies as dumb, but this one is
A romantic comedy that pretends it's not a romantic comedy by making fun of other romantic comedies, even though by the end it's rolling out all the cliches you constantly see in these movies. Justin Timberlake and Mila Kunis play Justin Timberlake and Mila Kunis because their characters are completely unbelievable. They do have some decent on-screen chemistry but that's not that difficult when you're playing yourselves. Perhaps if more time had been spent developing the script and less time snarking on other films and filling the movie with pointless cameos, something better could have happened.