Thanks to a magically endowed skull that comes from a Buddhist temple, a young executive who buys for a Chicago department store (Judge Reinhold) and his semiestranged 11-year-old son (Fred Savage) unwittingly exchange bodies, and each has to go through a few days living the life of the other. If this sounds familiar, writer-producers Dick Clement and Ian La Frenais and director Brian Gilbert have little up their sleeve to make it otherwise. While a few decent laughs are wrung from the situation, most of this movie seems motored by what SF writer James Blish once termed an idiot plota story that can only advance because most of its major characters are idiotsand most of the sexual complications aren’t so much explored as sidestepped. Still, the Chicago locations are pleasant, and most of the castwhich also includes Corinne Bohrer as the hero’s girlfriend and Jane Kaczmarek as his ex-wifedo the best they can with the premise. Unfortunately, the filmmakers’ imaginations extend no further than the basic gimmick, which is exploited mainly for silliness, and a lot of golden opportunities are lost in the process. (JR)