THERE'S A MEMORABLE scene in Back to the Future when Marty McFly fills in for the guitarist at a 1955 school dance. He decides to wow the crowd with a tune that technically doesn't exist yet: Chuck Berry's classic "Johnny B. Goode." Damn near the same exact scene happens in Hot Tub Time Machine, a very, very stupid new comedy whose best joke is its title. Nick (Craig Robinson) performs for an audience in 1986, and guess which song he pulls from the future? "Let's Get it Started" by the Black Eyed Peas.

Oh, how transparently this movie rips off Back to the Future; oh, how badly it fails to be one one-hundredth as funny; and oh, how incredibly terrible that Black Eyed Peas song is. Along the way, Hot Tub Time Machine also poaches liberally from Better Off Dead—even dragging that movie's star, John Cusack, into its fetid whirlpool—as well as last year's The Hangover, which basically means throwing in as many disgusting vomit jokes and as much naked man-butt as possible.

Nick and Adam (Cusack), along with their asshole friend Lou (Rob Corddry) and Adam's 20-year-old nephew Jacob (Clark Duke), travel via hot tub from 2010 to 1986, where they inhabit their younger bodies. They look old to us, young to all the other characters, and Jacob for some reason looks the same. They try to not fiddle with the past, but things invariably happen, and Jacob—not yet born in '86—begins to flicker out of view. (Remember when that happened in Back to the...? Oh, never mind.) The real problem is that Hot Tub assumes that this fake movie version of the '80s is inherently funny. It isn't. It's obnoxious and garish—in other words, about as much fun as a party where someone throws on "Let's Get it Started."