A rodeo happened at Madison Square Garden last weekend, but the finest ponies in the city seemed to be across the street at the Hotel Pennsylvania.

Look, there’s a grown man in fuzzy chaps, hooves and a horse hat! There’s another with a tail made of colorful yarn. And another with a stuffed horse tied to his head.

It was enough to make even seasoned New Yorkers scratch their heads and wonder if they’d ended up in some cut-rate Narnia.

Welcome to BroNYCon, a gathering of some 700 people — mostly male, mostly adult — who are fans of the cartoon show “My Little Pony: Friendship Is Magic.” Think of it as a much stranger, more dilapidated Comic Con where pony nerds gather to buy merchandise, meet talent associated with the show or just hang with like-minded equestrian lovers.

(Sample bit of overheard conversation: “Hey, bro. That’s a sweet-ass Trixie hat.”)

Is this some illusion or vision inspired by 16 Amstel Lights too many? Is that guy really dressed in what looks like neon-pink felt pajamas and a pink horse head? Here’s what we pieced together.

“My Little Pony: Friendship Is Magic” launched in 2010 and is an update of the 1980s toy and animation franchise that was built around plastic horses with pretty, pretty tails that little girls could brush. It features colorful characters such as Rainbow Dash and Applejack.

TV network The Hub initially aimed the new show at young girls. But then, driven mostly by online forums (especially on 4Chan) and YouTube, the pony fandom grew like wild among adult males, nicknamed “bronies.” That’d be brother plus pony.

“At first I was browsing a forum, and I saw a [photo] of a rainbow-maned pony flying faster than the speed of sound and making rainbows, and I was like, ‘Oh, my gosh! It just exploded rainbows!’ ” says Matthew Shempert, a 20-year-old from Texas who came dressed as something called Pinkie Pie.

“I came across a YouTube video of the pony doing awesome tricks. So I just started watching the show.”

“It’s not like other kids’ shows. It blew me away,” says Patrick Cariou, 18, from Edmonton, Canada.

“The production value is great, how it’s written. It’s something I don’t see in regular kids’ TV.”

The BroNYCon crowd was packed into a string of tight hallways and one large ballroom that smelled like a strange combination of sweat and smelly markers. Tables were piled with merchandise, including pony figurines, posters, shot glasses, T-shirts and stickers. The main attraction seemed to be the voice actors from the show, who sat politely at tables and signed merchandise for fans.

Artist Kate Moschella was there to sell sketches of the “Pony” characters.

“I did some marker outlines of them, and that was kind of popular,” she says. “I’m doing a pay-what-you-want sort of thing — $10 is the average. It’s been pretty good.”

Downstairs, Massapequa high school students Tyler Riebl and Joe Smith were shut out, having failed to buy advance tickets. (Everypony knows you gotta RSVP, fellas.)

Riebl, who estimates that about 25 percent of his school is into the TV series, is wearing a homemade sign around his neck that reads, “Free Hugs for Every Pony.”

“Online, I was seeing that a lot of people were depressed about not having any friends, and stuff like that,” he says. “So I’m here to hug everyone and make them feel better. About everyone I’ve met has taken me up on it so far.”

Paula Jacobs, a 21-year-old college student from Boston who was decked out in a purple Twilight Sparkle costume, says the series is huge in her peer group.

“I’d say 80 percent of my friends are into it,” says the “pegasister,” slang for a female fan. “My dorm loves it. We get together to watch the shows, and we eat and laugh.”

“My Little Pony” just returned for a second season last fall, and ratings reportedly doubled from the first. But even with growing popularity, mainstream acceptance for bronies is not always easy.

“My dad’s like, ‘What are you doing?’ They kind of look away,” Shempert, the Texan, says. “My sister thought I was crazy at first but then she’s like, ‘Yeah!’ My brother is like, ‘Don’t talk to me.’ ”

“My family is cool with it,” Jacobs says. “They think it’s a fad, but you know, it could be worse.”

reed.tucker@nypost.com