Kim announced her engagement to New Jersey Nets player Kris Humphries in May and the couple are planning to tie the knot over the summer.
Speaking on Lopez Tonight, Kourtney confirmed that she and sister Khloe are organising the bachelorette party and are determined to "embarrass" their sister.
"We are going to do whatever we can to embarrass Kim, just to bring her such embarrassment - that's our job!" she said.
George Lopez then questioned whether that might involve Kim walking around Las Vegas with a "penis hat", to which Kourtney said: "Oh yeah! We're going to do it all. We have so many tricks up our sleeves that she won't even know what is happening! Stay tuned!"
Khloe previously hinted that she would use Kim's bachelorette party as "payback" for her own bachelorette celebration, describing it as "the worst... it just wasn't sexy at all".
"I might just do a payback for Kim," she told E! News. "Kim does not like what she gave me, like penis straws and a little go-go dancer. Kim would cringe if I did that for her, so I might do that just to see what happens."
Humphries popped the question to Kim by spelling 'will you marry me?' in rose petals on her bedroom floor. Promos for the new season of Keeping Up With The Kardashians have hinted that the proposal will be shown in an upcoming episode.
> Kim Kardashian, Kris Humphries decide on wedding date?
> Khloe Kardashian: 'Kris Jenner is helping plan Kim's wedding'
Watch a promo of Keeping With Up Kardashians below: