John Cussak stars in Hot Tub Time Machine, a movie which as the title suggests in about a time machine that's a hot tub.
According to the synopsis, "The film depicts a group of unsatisfied men (John Cusack, Rob Corddry) who are thrown back in time to their younger days in 1986 via their Jacuzzi. Chevy Chase stars as a repairman who divulges his wisdom, and he may or may not be behind the travelling."
Yeah...ok. Due out 2010. Here's the Hot Tub Time Machine Red Band Trailer. it does have an R rating, but only due to some mild swearing.