Jehovah's witness question?

i have a friend who is a Jehovah's witness and whenever the holidays come up we invite her places. now her dad has said that she cant have worldly ociations which means that she cant ociate with people who are not JW. that is really annoying cause now she cant do anything with us. can anyone give ideas so she can come out again with us. and why cant JW's go with people who are not in there religion?? there missing out big time.