There is a Brony hater going around messing with Brony groups. DO NOT invite him to any group,DO NOT promote him in any way, and DO NOT accept anything from him. Avoid and block ~PublicX form your groups. Report any malicious activity form him. He is taking advantage of Admins by requesting to join a group as a Co-Founder instead of a member to gain access to the group that automatically accept members and admins. Change your settings so that any new Member,Co-Founder,any position that has access to the admin privileges does not get automatically accepted!
FOUNDERS-In the Admins Area tab, change the privileges of Co-Founder to either, can edit/delete some content or view only.
PLEASE pass this along to any and all Admins and Members of groups.