By Joe Brown (contact)

Wed, May 21, 2008 (2 a.m.)

Chris Morris

It was a big decision. Pretty much the biggest since senior prom.

Who was I going to ask to go with me to the Cher show at the Colosseum?

I had known for weeks that I was going to review Cher, but I was stalling about picking the perfect date.

The day drew near. I had to make a decision. Boss? Colleague? Hot clerk at Whole Foods?

Suddenly it struck me — I would take Cher to see Cher.

So I googled “cher impersonator las vegas,” as one does, and the top result popped up: Heidi Thompson.

She looked great, and her Bono-fides were in order: The real unreal deal, the first-call Cher impersonator in Vegas and perhaps the country, Thompson spent more than 12 years playing Cher in “Legends in Concert” at the Imperial Palace.

She is that rara avis in the look-alike industry — a female Cher impersonator. There are dozens (if not hundreds) of guys who can do a killer Cher, but only a handful of women.

As a plus, I figured Thompson might provide some insight and perspective. After all, she had spent hours, days, years inhabiting Cher’s songs, costumes, wigs, makeup and persona. Who could be better qualified to say whether Cher is doing a good job portraying herself?

So I made the call.

“It sounds like a hoot,” Thompson said. And she said it just like Cher! (Thompson told me later it took six months to nail Cher’s speaking voice.)

The night arrived, and I met her outside the Cher tchotchke shoppe adjacent to the Colosseum.

It wasn’t hard to figure out which one she was, even though she was not in Cher-wear. She was elegant in a black suit and hat, a Dolce & Gabbana leopard print peeking from her sleeves.

Reviewers are a nerdy, competitive lot, and I admit I enjoyed the double-takes and reflected attention. As I moved through the opening-night crowd with Thompson on my arm, I felt like man-candy for the first time (and probably the last time) in my life. Just for the moment, I imagined I knew how Cher’s pizza boy — Rob what’s his name, Camiletti — must have felt.

There were a few metamoments during the show, as it hit me that I was watching a simulacrum with a replica. During the big finale, as Cher belted out “Believe” with all 4,300 in the audience on their feet, Thompson leaned over and sang along in my ear. Cher in stereo, just for me.

That night I learned it isn’t easy being Cher.

Thompson doesn’t enjoy being mistaken for her meal ticket: She recently went to dinner at Rao and all the diners stood up and applauded as she entered.

“I don’t like that,” she says, “because I feel like I’m lying. I like it when they know I’m an impersonator and then they can laugh with me and I can relax and not worry about it.”

Cher takes up a lot of space in her life: A big room in Thompson’s Las Vegas house overflows with costumes and wigs.

The career highs are thrilling, but the lows are really low: Thompson has sung the national anthem as Cher before a Mets game at Shea Stadium. She has also arrived for a charity gig at a mall to discover that she and her fellow impersonators had to play musical chairs — on toilets. (“I did it, but I made sure I lost in the first round.”)

There’s no business like Cher business, and Thompson gets most of it. She left the show four years ago, but “Legends” still hasn’t replaced her. “Good luck!” she says, laughing. “Until I see somebody that could replace me, I’m gonna be cocky. There are so many impersonators that have multiples that are also good in their character. For them it’s more difficult — they have to be competitive with their pricing. For my character, I really don’t. I have people that do Cher that I’ll refer clients to if I don’t want the job.”

The funny thing is that Thompson never particularly revered Cher. A singer-songwriter, she had fancied herself more of a Streisand type, and often got annoyed when people kept saying, “You look just like that Cher.” But when the producer of “Legends” asked her to join his show — adding that he would triple her paycheck — she signed on to play Cher, two shows nightly, six nights a week.

“It turned out to be a trap for me,” Thompson says. “It was hard for me to concentrate on a real career with just Sundays off.”

After the show, Thompson and I did a very unCher-like thing, and decided we were too pooped to party on. Before heading home (her husband drove over to pick her up) Thompson pronounced it the best Cher show she has seen.

“She actually did Cher better than I do, which is rare.”