Puberty. Gotta face it. But where? In high school, opposite a bully's fist, getting slammed into the cold bathroom wall? Or on a tropical island, in fluctuating degrees of sweaty undress, snuggling with a nubile coed?

Get your lunch flushed down the john, or tan and writhe on palm fronds?

Flush or fronds?

The summer of 1980 gave us the choice. "The Blue Lagoon" and "My Bodyguard" came out within a month of each other. Essentially, they were teenage movies trying to act adult in a summer of grown-up comedies acting childish (the floating Baby Ruth in "Caddyshack," the big bags of weed in "Cheech & Chong's Next Movie"). But both had wildly different interpretations of growing up.

Two 7-year-olds and a ship's cook are marooned somewhere in the Pacific at the beginning of "Lagoon." After they build a state-of-the-art flotsam house (two bedroom, 1/2 bathroom, ocean view) and the cook dies, they grow into a teenage Brooke Shields -- looking a lot like an adult Denise Richards -- and Christopher Atkins.

Their bodies start to act funny. They're irritable, they "notice" each other. They do everything teenagers do, but with the mental maturity of 7-year-olds. They tease, they fight, they put off icky nudity until it can't be helped; they are wearing flora, after all, which disintegrates after a while.

The hero in "My Bodyguard" did not, alas, grow up in the vacuum of the tropics. Clifford Peache (Chris Makepeace) is in the trenches the first day of his sophomore year at Lake View High School in Chicago. His bully is the thuggish Melvin Moody, or "Big M" (Matt Dillon, who was 16 and had yet to grow into his ears and voice). Showing a keen sense for entrepreneurship, Melvin threatens the acned masses with bodily harm unless they pay him, daily.

When an antisocial, six-foot goon shows up at school, Clifford quickly makes friends with him. He can now fight bully with bodyguard. That is, until Melvin gets his own bodyguard.

Sex isn't a big part of "Bodyguard," but posturing is. It's all about intimidation and who has the bigger muscles. Survival of the fittest. The climax is a rumble during recess, bodyguard vs. bodyguard, bully vs. bullied. It's a throwdown of junglelike proportions, ending in blood and bruised egos.

In "Lagoon," there isn't much conflict, or climax, but it does broach the topic of societal discord.

"I don't understand why -- why people have to be so bad to each other," says Brooke breathlessly after seeing the island natives behead what is probably a tribal dork.

It's all part of growing up, you see.

Side by side at their 25-year reunion, it's obvious the films fit into the trend of their day. They were reactions to the adolescent romps of the late '70s ("Animal House") and precursors of the adolescent mood pieces of the '80s ("The Breakfast Club," "Sixteen Candles," all things Brat Pack). "Bodyguard" and "Lagoon" made opposite approaches toward the same goal: targeting young audiences with young casts but using a heavy, adult tone. The bodyguard could have been comic relief; instead he's a study of the vulnerability behind a Goliath.

Whether "Bodyguard" and "Lagoon" succeed as art is another story. "Lagoon" was the ninth-highest grosser of 1980, with a $58.9 million box office haul, but it was (and is) derided as a chaste, witless sex fantasy, a stutter-step from pornography. "My Bodyguard" took in $22.5 million, but was warmly received as a sincere representation of the challenges of youth, and a remake is currently in development at Miramax.

What do we have to learn from that summer now, as another school year has begun? These days, it's impossible to flush someone's lunch down the toilet without facing litigation. It's also impossible for 16-year-olds not to know the basic machinations of sex, even if they were stranded on an island at 7.

And for all their Grecian splendor, the stranded lovelies of "The Blue Lagoon" seemed like flashes in the pan, the yearbook's Best Looking couple that went on to steady jobs working in retail or food service (or patenting fishing lures and hitting the Broadway replacement circuit, in Atkins's and Shields's cases). Ignorance is bliss but bad for business.

As for "My Bodyguard," the bully learned his lesson. Earlier this year, Dillon, now 41, gave a weighty, rich performance in "Crash," his 34th film, which earned him overdue critical respect.

And just before that summer of 1980, he made perhaps the smartest decision of his young life: He turned down the male role in "The Blue Lagoon."

The young and the listless: Christopher Atkins and Brooke Shields in "The Blue Lagoon," a hit at the box office if not with critics.Matt Dillon and Chris Makepeace as the bully and his prey in "My Bodyguard," a modest commercial success but resonant thematically.