Khloé Kardashian Plans 'Very Embarrassing' Bachelorette Party for Kim Kardashian

By Emily Evans

07/13/2011 at 10:40 AM EDT

As Kim Kardashian plans her wedding to fiancé Kris Humphries, her sister – and maid-of-honor – Khloé Kardashian is also in party-planning mode.

"I'm having so much fun planning the bachelorette party," Khloé told PEOPLE at a HPNOTIQ Harmonie party in New York City Tuesday.

Though specifics of the bachelorette bash are still under wraps, Khloé did promise to participate in a time-honored tradition: embarrassing bride-to-be Kim.

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"My bachelorette party was very embarrassing [with] ... penis straws [and] everything penis-themed," Khloé, 27, said. "Kim is very uncomfortable with all that stuff, so I'm going to go all out and embarrass her, because it's just fun."

But will Kim, 30, get revenge on the day of her wedding by picking out unflattering bridesmaids dresses for her sister?

"Kim knows what she wants. She's someone, though, who'll put us in cute dresses," Khloé said. "She's not going to put us in something ugly to make herself look better – trust me."

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