The plot setup of the movie is that Joe Bauers (Luke Wilson, playing a low-echelon army librarian who is dead-average on all measures, including IQ), and Rita (a similarly dead-average prostitute [she's a prostitute for the slimmest of plot threads]) are put into hibernation coffins, ostensibly for a 1-year tes sleept. Due to a bunch of mistakes, they wake up 500 years later instead.
In the intervening 500 years, the story goes, the average intelligence has plummeted because stupid people breed so much faster than smart people -- such that Joe and Rita are the smartest people in the world. The future is garbage dumps the size of cities, gatorade knock-offs replacing water, and Jackass-type shows ("Ow! My Balls!") as the height of pop culture. You know, fiction.
The movie was released in a tiny number of theaters (reports vary on the number), for a week, before being dumped to DVD. This might have something to do with the sheer trashing of major corporations (Fuddruckers morphs into Futtbuckers, and thence to Buttfuckers, Starbucks becomes a brothel chain, and so on).
I'm hardly the only one to remark on the similarity of the movie's plot setup to C.M. Kornbluth's "The Marching Morons" (and "The Little Black Bag"), first published in 1951. That's only in the plot setup, though. Kornbluth's story, which posits a few million "elite" smart people running the world behind the scenes while the billions of "normals" think that it is they who are running it, is actually much darker and nastier than Idiocracy.
By the way, I strongly recommend against googling "idiocracy kornbluth". That seems to pick up every insane right winger who ever read (and seemingly masturbated to) the Kornbluth story. I'm still feeling nauseated after reading some of those.