File this one under "Holy Crap WTF". Chicken pox parties were something I'd heard of, but this takes it to a whole new level.
This closed Facebook group, which calls itself the "Measles Mumps and Rubella Immunity Network" describes itself like this:
This group is for those who respect the differences in the different parenting and lifestyle choices seeking alternative or holistic approaches. The purpose of this group is to notify when MMR is in your area. If individuals chose to expose themselves or other individuals it is on their own accord.
This group is not here for debating, supporting, or preventing of MMR. This is also not a vaccine informational, debate, support group; there are a lot of Anti and Pro Vaccine groups to find that information.
There's to be no moralizing or philosophizing about vaccinations or lack thereof. Due to outside individuals who disagree with alternative parenting claiming child abuse, and threaten with lawsuits:Before You Judge, or make claims:Whether you decided to vaccinate or not for any disease there are possible risks and reactions which you can not predict once exposed. You are the judge of what benefits outweigh the risks in your approach to vaccinate or not.
Please no spamming, soliciting, harassing, or advertising. The only exception on advertising will be for other MMR related groups and other groups such as natural immunity/anti-vaccine/ or childhood exposure diseases; this exception does not apply to discussing the topics- just where you find the group. If we find you to be going beyond this scope we may or may not remove the post or you from the group at our discretion. If you are not a member we will message you, and request you stop or we will report you to Facebook.
Friendly reminder: these diseases can cause additional complications, including pneumonia, spontaneous abortion, fertility issues, encephalitis, and even death. Also, by actively spreading infection, you are putting immunity-compromised people at risk, especially as you are often contagious even when asymptomatic.
Update: It looks like the group was now either taken down or switched over to secret status on Facebook. Here's a mobile screen shot of their group as it existed before, unfortunately without the whole blurb extended.
Update 2: The group appears to have a smaller spinoff, the Rubella Immunity Network, which uses similar language in their description. A screenshot of the smaller group is shown below.