This is just me... but I would jokingly set up my place to where it would look like something out of a Hippy-Spiritualism movie, and when they come... have them join in bazaar rituals (I would just love to see their reactions

).
In all seriousness, though, you are in my prayers. With something like what they are doing, you can expect that the same major themes about Catholicism will come to the table. Given that, it will be easy to anticipate the "problems" that they will try to show you.
I agree with all that has been suggested, they are great ideas! I especially like the idea about setting the mood of your house to be peaceful with music and a nice dinner. With that, think ahead about different scenarios that may happen, and how to peacefully resolve it.
Give real-world (tangible) examples of Catholicism. What I mean by that is, say for instance, they bring up Saints, Statue Worship, Mary Worship, Images in house, etc. You could, somewhere in the conversation,... distract them the negativism, and show them some pictures of your children, or wedding that you may have displayed.
Tell them about the event, or something special about that picture, and tell them about how much that picture means to you/ how much memories that picture brings to you. This is easy to set up a connection with "Statue worship,... etc.". For instance, you can say things like "Is it wrong for me to have these emotions when I see these pictures?... Am I really having these feelings because of the picture, or the events/people the picture reminds me of?..." and begin to explain basic Catholic Doctrine.
Personally, I like to think that Jesus spoke in parables because no matter what He would have said plainly, the people would have had a harden heart and not accept His views. By speaking in parables, He gave "real-world" examples that got the people to honestly think about His message (no matter what their bias was).
Don't try to change minds, but try to connect with your friends and explain questions they may have (even though they may try to change you).