Khloe and Kourtney Kardashian touched down at LAX airport Tuesday night -- they were returning from a trip to NYC. We caught up with them and Khloe revealed who will be sister Kim's maid of honor -- so, is it her or Kourtney?

"Both of us!" she said. Guess that makes Kylie and Kendall bridesmaids. Khloe also talked about her nipple slip on Fox News Tuesday, and told our reporter how hubby Lamar felt about it!

    "It's not embarrassing. It's not my vagina. ... Trust me -- he [Lamar] loves my nipples more than I do."

In the vid, Khloe carries nephew Mason -- check out how cute he is!

Hopefully there will be a wedding ... online reports Wednesday claim that Kim cheated on Kris!