A hired-gun car salesman (Jeremy Piven) and his crew of eccentric sales associates (Ving Rhames, David Koechner, Kathryn Hahn) come to the rescue of an ailing California dealership during a three-day Fourth of July blowout. This frantic, vulgar, but often clever comedy seems to have been inspired by John Landis’s little-seen documentary Slasher (2004), though the dealership’s rivalry with a neighboring car lot may also call to mind the old Robert Zemeckis classic Used Cars (1980). It’s a grab bag of comic ideas, but some of the gags are impressively perverse (like Hahn’s lust for a ten-year-old boy whose glandular abnormality has turned him into a full-grown man). First-time director Neal Brennan is best known for having partnered with Dave Chappelle on the cult sketch-comedy series Chappelle’s Show; the cast includes Ed Helms, Ken Jeong, and Rob Riggle. R, 90 min.