In last weekend's hit ''13 Going on 30,'' Jennifer Garner's teenage self time-travels from 1987 -- which just happens to be the year that Hollywood's obsession with age-swapping comedies began. Over the years, it's been hard not to notice a few recurring themes among this odd minigenre's films. Are they all actually the same movie? You be the judge:
''13 Going on 30'' (2004)
STAR Jennifer Garner
SCENARIO Magical ''wishing powder'' changes a 13-year-old Jenna Rink (Christa B. Allen) into her 30-year-old self (Garner) overnight.
FASHION FAUX PAS Jenna wears a camisole to the office.
CREEPY SEXUAL SITUATION Jenna is horrified by the sight of her live-in hottie boyfriend's ''thingy.''
CHILDISH WISDOM PREVAILS WHEN... Jenna saves an office party by doing the zombie dance from the ''Thriller'' video.
''Freaky Friday'' (2003)
STARS Lindsay Lohan, Jamie Lee Curtis
SCENARIO Magical fortune cookies cause Tess Coleman (Curtis) and her daughter Anna (Lohan) to swap bodies.
FASHION FAUX PAS Anna gets her mom's ear cartilage pierced.
CREEPY SEXUAL SITUATION Tess is horrified when her daughter uses her aging bod to woo a teen hottie (Chad Michael Murray).
CHILDISH WISDOM PREVAILS WHEN... Trapped in Tess' bod, a clueless Anna is forced to promote her mom's new book on an ''Oprah''-like TV show -- but saves the lame appearance by crowd-surfing.
''18 Again!'' (1988)
STARS George Burns, Charlie Schlatter
SCENARIO Magical car accident causes Grandpa Jack (Burns) and his grandson David (Schlatter) to swap bodies.
FASHION FAUX PAS David shows up on campus dressed like, well, George Burns -- and making vaudeville-era wisecracks.
CREEPY SEXUAL SITUATION A hottie coed wooed by David would be horrified to know that she's actually making it with an octogenarian.
CHILDISH WISDOM PREVAILS WHEN... Actually, it's Burns' (very) old-school wisdom that prevails since the kid spends his time in Grandpa's body locked in a coma. (Nothing says ''comedy'' like ''coma.'')