Think you know everything about Paris Hilton? Think again! Tonight on ET, meet the real Paris: The headline-making actress, socialite, singer and entrepreneur gets real with Mary Hart in an insightful one-on-one interview on the all-new ET set, talking about everything from her new MTV show to her love life, that McCain "celebrity" campaign ad -- and last summer's highly publicized jail incident.

"I'm not like what most people think," a candid Paris tells Mary.

Indeed, Paris openly talks about going to jail for a probation violation (driving while on a suspended license, stemming from an alcohol-related reckless driving charge) last June, agreeing that it was the toughest thing she ever had to do in her life.

"That was really hard, but it made me a stronger person," she says. "[It was] an experience I'll never forget -- and never want to repeat."

As for her humorous and clever response to being featured in John McCain's recent campaign ad, in which he compared Barack Obama to Paris and Britney Spears' celebrity status, Paris says it was all in a day's work.

"I was brought into it and I enjoy laughing at myself; I was showing people that I can do that," she says. "I thought it would be fun. I shot it at my parents' Hamptons house."

Now, Paris is at it again with a new show debuting on MTV September 30 called, "Paris Hilton's My New BFF."

"Girls and two boys compete for the chance to be my new [best friend forever]," explains Paris. "I make up all the rules, and these kids are not gonna know what hit them."

Paris puts them all to the blindfold test, seeing how they'll respond to embarrassing questions when they don't know she's there. She tells Mary that finding true friends in real life hasn't been easy.

"Certain people sell things to the [tabloids and] do things you think a friend would never do to you," she says, adding that she deals with the betrayal by cutting them off -- completely. "That's it -- someone does that to you once, you can't trust them again."

So, does she have a current BFF? "Nicole [Richie] is my best friend," says Paris, indicating that her highly publicized rift with her good pal and "Simple Life" co-star is in the past. And spending quality time with new mom Nicole and her baby daughter Harlow with rocker Joel Madden has definitely put Paris in a nesting state of mind.

"I'm in a really great relationship right now [with Joel's brother Benji], and we're really happy, and one day I would love to have children," reveals Paris, also addressing engagement rumors with the answer, "We're boyfriend and girlfriend. He's an amazing guy. He's also like my best friend. He's just so loyal, so sweet, does nice things for me all the time. We're very in love."

Watch ET for more of Mary's interview with Paris!