Watch the full Kim and Kourtney Kardashian interview tonight. "Piers Morgan Tonight" airs weeknights on CNN/US at 9 p.m. ET and on CNN International at 1200 GMT/1300 CET/2000 HKT.

(CNN) -- The sisters Kardashian -- Kim, Kourtney, and Khloe -- don't have to spend millions on focus groups and dynamic PR strategists to get noticed: Twitter does it for them.

In an interview to air on Thursday's "Piers Morgan Tonight," Morgan pointed out that all three are in the top 100 list of people being followed on Twitter worldwide: Kourtney is number 72, Khloe is number 47, and Kim is the sixth-most followed. With 6 million followers, she's neck and neck with President Barack Obama.

Kourtney called Twitter "the best decision-maker," pointing out that she Tweets everything from potential perfume bottle designs for the sisters' signature fragrance, to outfit dilemmas, to asking fans what she should have for dinner.

Morgan, who has only been on Twitter for six weeks, has more than 200,000 followers, and asked Kim and Kourtney to help him gain more, pointing out that the sisters' influence was "fascinating."

In light of the fact that their opinions are clearly in demand, Morgan asked them about Obama and Sarah Palin, stating, "What would you say if I said, 'Sarah Palin'?"

To which Kourtney replied, "I just think, like, hunter. That's just like the first thing that comes into my head.

Kim said that Obama was the first presidential candidate to get her "motivated enough to vote."

When Morgan asked Kourtney and Kim if they would have any talent if they were to appear on "America's Got Talent," Kim Kardashian said, "I would absolutely say that marketing is a skill." Kim also said that "fashion" was a skill, pointing out that the sisters all worked as stylists at some point and that they currently own "three successful clothing stores."

The Kardashians pointed out that much of their brand revolves around promoting a healthy body image and that none of the three sisters are "stick skinny." Kourtney admitted that while she is, in fact, a size zero, she is also very petite at 5 feet tall, and curvy. Kim, at 5-foot-3, said her size wavers between the 4 and 6 range. "We're not trying to fit in the same mold," said Kim. "We know that we feel our best when we look our best."

Kim said she is always "super honest" when plastic surgery rumors surface and had no trouble admitting that while she has "tried Botox before," her breasts are "completely, 100 percent real." Kourtney admitted she does, in fact, have implants. Kim also said she often uses body shapers, masking tape, and other under-clothing body smoothers to boost her confidence -- particularly on the red carpet.

"If you know your body type," said Kim, "then you can dress to feel -- its like, 'Fake it until you make it' is what we always say."

When Morgan asked them what the most extravagant thing they ever bought for themselves was, Kim said she had purchased a $115,000 watch that she "got a really good deal on."

Even the most savvy pop culture connoisseurs may not realize that Ryan Seacrest is the Kardashians' boss. Seacrest has served as executive producer of the E! network's "Keeping Up with the Kardashians" since the reality series premiered in 2007.

"He is pretty evil," joked Kim.

The Kardashians count Seacrest among their greatest friends. "Ryan is so easy to talk to. He just gets it," said Kim. "He completely trusts us and our vision."

Morgan also asked the Kardashians if there is anything about their lives that is off-limits.

"Relationships," said Kim. "I only show very little bits and pieces." When Morgan asked Kim if she was "in love" with New Jersey Nets player Kris Humphries, Kim was tight-lipped. "I think that this time around, I am really trying to keep things a little bit more private than I have in the past," she said.

The Kardashians were quick to point out that their solid American values and work ethic keep them grounded. Kim, who said she "never" talks money because she thinks its "inappropriate," maintains that she gives 10 percent of her yearly income to her church because that's how she was raised.

"Whatever it is, I give 10 percent away to the church, and that's what I was taught." When asked if she did the same, Kourtney said, "I'm going to now," with a laugh.

"I was taught that, too, but I forgot about it."

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