The "Sling Shot" in Coney Island. (Frank Franklin II/AP)

“Oh my God, Aiden! Oh my God!” I cried in terror.

My 12-year-old nephew giggled in delight.

After surviving three turns on Coney Island’s Cyclone roller coaster, we sat next to each other in a circular ball, described as an “open-air cockpit preparing to launch and providing a near out-of-body experience.” I debated changing my mind when a large siren blared. Too late — we soared above the park at 90 mph in the Sling Shot.

“We’re going to die!” I screamed.

My co-pilot yelled, “Awesome!”

Twofold terror struck me at 150 feet: I felt out of my body and possibly out of my element tackling this role as a temporary parent.

Inviting my nephew to visit for a few days had seemed like a great idea. I had always enjoyed bonding with him and his 9-year-old sister, but it had been in limited amounts and rarely one-on-one.

Single, gay and 49, I had started to face the prospect of a life alone mixed with the tinge of regret when others asked, “Do you still think about having kids?” The idea seemed preposterous at my age.

Living in New York City, I enjoyed late-night cocktails and a lifestyle with no strings attached. I had a busy career as a corporate writer, earning enough to travel untethered from the constraints of a family — in stark contrast to my sister, Kelli, who raised her children in the small, working-class Pennsylvania town where we had grown up.

I didn’t envy the chaos of her life: soccer practices, screaming kids and shuttling carpools. Yet I yearned for what she had created, raising a family and the pleasures she would have watching her brood take flight as they grew up.

“I could take Aiden for a week,” I had blurted out months earlier.

Without much thought, I had invited Aiden to spend a week of his summer break with me, a 2½-hour bus ride from his home.

Kelli expressed concern. “What would you do with him all week?” she asked, skeptically.

I reiterated the first selling point — there would be no driving. Years earlier, I had notoriously fallen asleep behind the wheel, driving home from my niece’s third birthday party. I woke with the left car wheel grinding against the middle barrier of the highway.

She forbade me to drive anyone, especially her children, anywhere, ever.

Beyond that, she quickly came around to sending Aiden my way.

And then the reality of my promise started to settle in: “What does he eat for breakfast?” I nervously asked.

“Whatever,” she casually replied. My sister realized she would only have one kid — my niece — on her hands for several days with her eldest in my care. I suspected she was getting used to this idea pretty quickly.

I hid all my cocktail fixings and stocked up on Snapple and Fruity Pebbles — the only two requests I received from my nephew, via my sister.

I booked a family musical for the first night. A diner near the theater seemed like an easy option for dinner, yet Aiden, with his Bieber-coiffed blond hair newly cut for his big trip, was overwhelmed with the options. He settled on fried chicken, ignoring it while he ate the potatoes and sides around it.

“Eat your chicken or no cheesecake,” I warned, knowing he was desperate to have dessert. Flexing my disciplinary skills felt unfamiliar as my fun uncle vibe took a back seat to stepping in as his faux father. I could easily scold him; not so sure I could dole out a mini-punishment in public.

This visit would be a crash course in (and, yes, I know just a glimpse of) the reality of parenting:

The two times Aiden showered at my apartment, the towels and bath mats were sopping wet when I assessed the damage. Had he taken it all into the shower with him? I was perplexed at the gobs of toothpaste left in the sink and splattered up the mirror. Did anything make it to his mouth? While I went about the daily tidying up of my studio apartment, Aiden and his lanky legs lounged on my delicate, blue chaise sofa, playing video games on his iPhone, blaring sounds hidden from me by his wireless headphones. I fretted about the cereal bowl and the splashes of milk that left splotches on my postmodern coffee table.

“You have to watch!” I flailed my arms to wake him from his private game land.

“Sorry, Uncle Scott.” He moved one headphone off an ear to acknowledge me, wiping the stain with the palm of his hand.

But for most of the trip, we assumed our roles as uncle and nephew. We became detectives during a spy museum tour, treated ourselves to bad food and racked up high scores at the arcade where I lost sight of him and panicked, knowing I would never tell my sister I took my eyes off him for even a second.

We also tackled every wild ride in Coney Island, including the Sling Shot.

The commemorative $15 video clip I purchased afterward revealed a child delighted floating high above the park and an adult gripping a ride in fear. My favorite part was watching the moment where we caught a breeze and the ball seemed suspended in time. The sun shone in the background and all I saw was blue sky, clouds and the widest smiles on our faces.

I rarely smile like that. My single city life affords me laughter, loads of fun and unwelcome feelings of loneliness. I had traded starting a family with the adventure of forging a life on my own. Was I missing out by not being someone’s dad?

“Did you have a good time?” my sister asked her boy when I returned him in one piece.

“It was great. I can’t wait to go next year, “ Aiden said.

“Next year?!” I responded.

“Looks like this is an annual thing. You’ll need to take that one for her own trip too.” My sister pointed to my niece.

“I don’t know if I’m ready,” I said.

“This is how it is,” she said. “When you do something with one, you do something with the other. Being a parent is challenging.”

I certainly got that now, along with the honorary title of being the “cool uncle,” as the comments on our social media thread noted when viewing our hair-raising video clip.

Braving the ride proved the parent gene exists somewhere within me. My parental possibilities are improbable now, but I love discovering that I can play a significant role in the family I chose to create. That is a compromise worth embracing. I won’t be forgotten or lonely as I age, and I can put my dad skills to the test with someone else’s kids. With kids I love.

“Do you really want to come again next year? “ I asked Aiden.

“Sure.” He barely looked up from his phone. “You’re all right.”

It was a small seal of approval from any teenager.

Luckily my niece fears big, scary rides in favor of making homemade slime. Maybe that will make it easier for this novice parent-figure to keep an eye on her. And now I have time to get up to speed on all things slimy, while finding a suitable cover for my coffee table.

One thing remains certain: I liked trading my cocktailing and single nights at home for kid-friendly snacks and playing parent. I have newfound confidence as a suitable role model for my sister’s kids. And it’s a role that fits just right.

Scott Gerace is a writer living in New York City. Find him online at scottgerace.com.

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