It’s hard to get a leg up in this town — so one college student is getting a foot in the door instead.

After responding to a Craigslist ad last year, a 19-year-old NYU student became a “foot prostitute,” offering up her toes to men for the promise of $500 to $800 a week part-time.

“I’m only young and living in New York once,” says Olivia, who declined to give her full name.

The ad, which said, “Girls With Pretty Feet Needed (age 18-30) (Lower East Side),” asked for only her name, phone number and a head shot.

“It only took them four hours to contact me back,” she says. “They told me to get a pedicure and dress like you’re going to a club.”

The event took place Thursday at a Midtown spa, where regular hours feature routine services such as scrubs and massages. After dark, it’s decorated to look like a bordello.

More than 30 girls wait in the lobby dolled up in corsets, 5-inch heels and speaking everything but English.

“I thought they said dress like you were going to a club; apparently, I came a little overdressed,” Olivia says.

Wearing pants, a dressy tank and black stilettos, she quickly hugs the wall, nervous she was scammed into sex trafficking.

The man who placed the ad walks in, pointing to some and moving them into another room. Olivia and the herd of those selected walk into the smaller room where two chairs sit ready for interrogation. He tells the girls one by one to sit in the opposite chair, then demands they bare their soles.

“He was looking for high arches and small feet,” Olivia says. “I guess that’s what they like.”

She’s a size 6 1/2.

Grabbing each foot, he analyzes the profile, bending them down then up and checking for hangnails or hammertoes. Only 10 girls pass the test. The rest get sent home unpaid.

“It took place at a spa but with lots of couches and massage tables and a liquor table that was literally a reception desk covered with alcohol the men were told to bring because the spa legally can’t sell liquor. They brought the girliest drinks possible, whipped-cream Svedka, cherry flavored vodka,” Olivia says.

After the girls get a little liquored up, the men appear. About 30 walk in, one by one, with their salt-and-pepper hair and big stomachs, each paying a $100 entrance fee to the foot pimp.

“The men made it a point to tell us this was their first time,” she says, “even though they already knew some of the girls by name.”

A finance man with a little potbelly invites Olivia to a private massage room.

“The ad said it was 400 bucks a night, which is very enticing,” Olivia explains, “but the guy in charge explained it’s $20 per 10 minutes” — so you’d need to see a lot of clients over a lot of time to make that happen.

They walk in together, he closes the door and she sits on the couch.

“At first I didn’t notice the napkins, lotion and wipes in the corner of the room and then you start piecing it together,” she recalls.

It’s her first time but she never feels uncomfortable. He constantly asks if she is OK with what he’s doing as he rips her black stilettos off with his teeth, massaging her calves, groaning while sucking her toes clean.

“It was weird at first. I mean, I thought he was just going to kiss my feet. Not put my whole foot in his mouth.

“He was polite,” she says, explaining how he kept his clothes on as he gratified himself.

When freshened up, he thanks her, says “I had a lovely time,” pays her and wanders back into the main lobby to find another foot to kiss.

The fancy footwork lasted 40 minutes. With tip, she made $200.

“If you’re an amateur you don’t really know what to do with your feet. This body part you normally use for transportation is all he wants. I needed to find ways to move feet in a sexy way, which is a challenge for that long.”

Around the liquor-filled reception table, the small talk depends on the guy. Some guys chat for 30 seconds and invite you to a room while others just want to talk to a pretty girl. “You could tell the guys were really nervous about what’s going on in that foot club,” Olivia says. “It wouldn’t surprise me if a lot of the info given was fake.

“There was so much sexuality with little effort,” she says, explaining the club’s strict clothes-on policy. And $200 for a young student in a demanding university with an unpaid internship is a pretty good deal.

“If I’m being honest, there are other ways to make money. But I do consider myself a broke college kid even with my allowance.

“I’ve taken a couple sexuality classes at NYU so I had a preliminary idea on fetishism but in practice it’s a little different. These guys aren’t hurting anyone and everyone’s got their thing that turns them on.”

Most girls have multiple footmen, and Olivia will gladly do it again.

“I didn’t break the law. I didn’t take off my clothes,” she says.

“Yes, I showered and changed into clean p.j.’s after, but my morals are still intact.”