Gym dance classes – why do I always make that mistake?

I go thinking they’ll transform me and I end up feeling like a clubfoot stuck in “Fame.”

I’ve tried hip-hop lessons – only to get lost on the first step of a J-Lo routine. I’ve suffered salsa classes – where I banged hips with fumbling bankers. I attempted Capoira and my bum hurt so much I couldn’t sit down for a week.

And last week, again, I got suckered. This time by a Dirty Dancing lesson inspired by the movie “Dirty Dancing 2: Havana Nights.” What was I thinking?

Well, actually I was thinking this: that good dance can be better than sex – or so they say. So while my life has been lacking in the one department, why not make up for it with the other?

Recently I’ve gamely hit the dance floor at almost every bar/party/club I’ve been to – and (with the help of 10 margaritas) occasionally convinced myself that I’m the sassiest chick in the room.

I was even beginning to think that dancing might be my key to happiness.

For example, the evening I got blown off by the actor in L.A., I soon repaired my spirits by leaping around to Blondie with a male friend at a party. We may have looked like a couple of deranged prom-goers – but I still felt like a dancing queen.

A couple of weeks before that, I spent three blissful hours grooving and grinding with a sure-stepped co-worker at a warehouse party on Canal Street.

We could have been Johnny and Baby in the original “Dirty Dancing” – until we got back into the office.

Inspired, I went to see “Havana Nights” on Monday. It wasn’t a good film, but I didn’t care. I fell madly in lust with the movie’s male lead, Diego Luna – he reminded me of the Buenos Aires lawyer I had a romance with two years ago.

The next day my mate Michele let it slip that she was going to a “Dirty Dancing” lesson at her gym. Dreaming of hot Cuban dance parties, I begged her to take me.

We turned up at New York Sports Club on 14th Street last Wednesday.

But the class was full of girls – except for a scary group of people at the front who looked liked the kids from “Fame.”

I had a horrid flashback to my hip-hop dancing lesson – and knew I’d deluded myself once again.

Almost immediately, the two teachers – who were wearing a trendy combo of ripped combat pants, sweatbands and mini-tanks – burst into the most complicated dance sequence ever.

As they spun, shimmied and high kicked, the people in the front row all whooped and shoulder wiggled. Michele and I cowered.

We’d hoped for a tip or two on how to move our hips Cuban-style (a feat I have woefully yet to master). Instead, we had to take each other as partners and launch straight into the routine.

While the students in the front (who I grew to despise in that one hour) danced like pros, the rest of us muddled through with no hope.

I had to grab Michele’s hips while she leg-kicked and stuck her bottom in my face. She was supposed to turn and give me “sexy eyes” – though “fish-eye” would have been more accurate.

At the end we had to shimmy at each other seductively – and we looked like a pair of elephants on heat.

When the class finished I wanted to go kill myself in the locker room. Instead, Michele dragged me to the front where the teachers and a couple of the kids from “Fame” were still hanging out.

“That class was a bit, well, advanced for us,” said Michele. “Is there anywhere we could learn something more basic, like how to move our hips?” she asked.

One of the girls looked us up and down. “Try having more sex,” she said as they all burst out laughing. I felt like punching her in the face.

So I guess the real lesson is this: That just like sex, dancing can make you feel like the hottest person on earth – or the most graceless frump ever born. To get it right just takes practice and confidence.

So I, for one, won’t be crushed by the posers in New York Sports Club. I know my Diego Luga is out there. My next stop is La Belle Epoque.