I'm a member of the Knights of Columbus. Aparently we're all supposed to get some signal from the pope to kill all protestants. At least that's what someone told me when I brought up the fact that I was in the KofC. I think the signal is the pope coming out and waving at everyone...
I'm not sure of the other secret stuff either. I joined because I went to a few church events and the KofC were the guys in charge of cooking burgers and dogs while drinking beer (anything to help the community).