Popular Halloween costumes: Witches, superheroes, athletes, oh my!

Grown-ups want to be witches while kids are opting for princesses and superheroes.

At least that's the expert assessment of what partygoers will choose as

sexy pajamas

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Almost 6 million adults are masquerading as a witch — black hats, warts and all – followed by vampires in the No. 2 spot (with 3.2 million people donning fangs and capes), according to the National Retail Federation.

As for kids, nearly 10% are set on Cinderella, Snow White or other princess frocks, while another 10% are favoring Batman and Spider-Man costumes. The superhero uniform also makes the Top 10 list for adults.

“The biggest theme this year is superheroes,” said Julia Darrenkamp, spokeswoman at Party City. “That is due to all the blockbuster movies this year like the Avengers, Spider-Man and Batman, which are popular with men and women.”

Revelers are also looking to the year's big events for costume ideas. Inspired by the London Summer Olympics, more than 1 million people will sport some sort of athlete uniform this year, the retail group said.

With the elections just weeks away, more than 760,000 politically conscious partygoers will don some sort of political costume.

“We'll see plenty of Barack Obama and Mitt Romney look-alikes out and about for Halloween,” said Pam Goodfellow of the research firm BIGinsight. “However, we expect these rivals will be able to find some common ground over the punch bowl or a bag of candy.”

Halloween is a big business for the costume and candy industry. People are expected to spend $8 billion on the holiday this year, the survey said. Nearly $3 billion of that goes to costumes.

Fergie is pulling off the Lindsay Lohan look way better than Lohan is these days.

The 37-year-old singer donned a long blond wig, and posed for a photo that she posted on Twitter, writing:

"What ever am I going to be for Halloween this year?"

Though she could be going for any number of costumes involving a blond wig, we think the pop star should settle on going as Lohan, since Fergie looked almost identical to the actress, who had extremely blond hair back in November 2004.

The singer is a big fan of Halloween, and last year she attended Heidi Klum‘s Halloween party, held at the PH-D Rooftop Lounge at Dream Downtown, dressed up as a child beauty pageant contestant from TLC's "Toddlers & Tiaras." She wore a poufy, purple sequined dress, a giant crown and carried a large purple teddy bear.