This spring break, I discovered that in the scant weeks since I departed for school in January, this “my brother growing up” business has gotten way out of hand. Danny is now a monster. He is a 6-foot-1-inch, aftershave-wearing, girl-ogling teenage beast.

I felt like an unsuspecting scientist returning for a routine stroll around the lab to discover this ill-conceived experiment in testosterone and over-sized carpenter’s jeans gone horribly wrong. Picture the Blob, only with fewer table manners and more libido.

It would have been nice to get some kind of warning before I stepped off the plane to discover a brother three feet taller, now sporting proto-sideburns two or three follicles strong. Someone could have thought to mail me one of those postcards magazine companies send when your subscription is running out:

“Dear Ms. Worthen. This is your last chance to savor the image of your pip-squeak brother in braces and L.A. Gear Lites high-tops! Don’t delay!”

People tell me this is completely normal. One night, as we sat at the dinner table, Dan heaped a third helping of spaghetti onto his plate.

“Hey Molly,” he began, his voice husky and thick with a mouthful of tomato sauce. “The theme for the Youth Center dance tonight is the ’70s. Should I do my hair in a pompadour, even though I don’t have that much hair, or should I do something, you know, a bit more individualistic, like with lots of little rubber bands?”

“What do lots of rubber bands have to do with the 1970s?” I asked. I would be no part of this. Dan shrugged and changed the subject to rant about “David,” who has been making comments in the locker room that purport to challenge my brother’s unquestionably masculine sexuality. “He better watch out, or he’ll be catchin’ fillings!” Dan exclaimed, smoothing a hand over his hair.

“What does that mean, Danny?”

“It’s a hip-hop term.”

A hip-hop term. I cleared my plate. It was sobering to think that four years ago, I had spent hours giggling at sleepovers, pining for boys exactly like this. I thought of those colt-legged, lip-sticked harlots who constantly call during dinner.

Impossible. I was never one of them. A lump swelled in the back of my throat.

Later that night, Dan returned from the dance disappointed. “It was okay. There weren’t any women there — just a bunch of freshman hose-bags.” He unlaced his Doc Martens and dropped them on the floor with a startling clunk.

My father glanced up quizzically. “What’s a hose-bag?”

“Dad, don’t take it literally. I’m using a euphemism.” He strutted off.

Yes, I think my brother is ridiculous. And this has made me think: Is this what happens when we get older? Do we look back over our burgeoning adulthood and dismiss it all with an eye roll and a chuckle?

I imagined my parents hanging up the receiver after my Sunday night phone calls and laughing for hours over my pathetic resume worries and room draw concerns. I realized what a giant hypocrite I am.

And the truth is — as much as I laugh and recount his escapades to my friends — in many ways, Dan’s more on top of his game than I’ll ever be. When he visited Yale last year, I brought him to a party. The moment we stepped inside, his voice mysteriously dropped three octaves: “Mind if I loosen up a bit, Molly?”

Within two minutes he was nowhere to be seen. After a frantic search, I swung open the bathroom door to discover my brother, one arm around the keg, hamming a mile a minute and surrounded by a chuckling ring of upperclassmen. One elbowed another, “Can you believe this kid’s in high school?”

No, sometimes I can’t. I’m nostalgic for the autumn afternoons spent frolicking in the leaf pile and grinding his face into the damp, worm-ridden underlayer. I miss sitting on his head every time he beat me in Super Mario Brothers 3.

But according to the various university admissions offices that send him brightly-colored propaganda, now he’s Mr. Daniel Worthen. According to the Illinois Department of Motor Vehicles, now he’s mature enough to propel a ton of steel down public highways.

According to me, he’s still a little punk. He is amusing, frightening and incomprehensible all at once.

Molly Worthen is a sophomore in Jonathan Edwards College. Her columns appear on alternate Mondays.