I am almost certain somewhere that Phil made mention of an update to prevent this from Happening, Why will you just add me to a random group that portrays nothing of interest to me. Its this guy and one Yogi guy and both are verified users, yet they spam more than bots here :(
This update has been published as of today. Now all group invites, except groups you are admin off trying to add yourself to, will go to the groups -> Group Invites tab before you are added to them. This will give users the abillity to approve/deny group invites :)