As amusingly stupid as advertised, Hot Tub Time Machine milks the ‘80s for laughs but gets most of its comedic mileage out of a more general strain of boys-being-morons insanity. In Steve Pink’s visually cruddy film, Adam (John Cusack) is reunited with friend Nick (Craig Robinson) when their high-school buddy Lou (Rob Corddry) almost kills himself via car exhaust fumes while rocking out to Motley Crüe’s “Home Sweet Home.” To cheer Lou up, Adam and Nick – along with Adam’s nerdy virgin nephew Jacob (Clark Duke) – visit an old ski resort haunt, where they jump in their room’s hot tub and magically transport back to 1986, where everyone sees them as their younger selves. This scenario, and the guys’ ensuing attempts to not change anything about their pasts (because of the butterfly effect), leads to a fair share of jokes about ‘80s fashion and politics, of which about a quarter hit their intended mark. Yet amidst the uneven period goof-offery and plot strands that find the characters learning about themselves, the story mixes ribald lunacy with wink-wink knowingness to witty effect, with the cast’s easy, rambunctious rapport leading to a raft of lewd back-and-forths often laced with sorrow over youthful opportunities squandered. Shakespeare it most certainly isn’t, but the self-consciousness of Hot Tub’s silliness turns the film into an invitingly idiotic ride, one marked by a standout Rob Corddry performance as a belligerently boorish prick with a tongue made for both malice and hair metal.