On facebook a friend added me to a group, and I never received a request or anything. I was just automatically added without my knowledge.
How do I block this from happening again?*** <---- this is the question I want answered.
Answer on Why can people add you to groups without your permission?
Well I looked it up because I was rather curious myself and this is what I found...
"Can I prevent people from adding me to a new group?
The functionality of approving a group membership is not available. Similar to being tagged in a photo, you can only be added to a group by one of your friends. When a friend adds you to a group, a story in the group (and in News Feed for Open or Closed groups) will indicate that your friend has added you to a group.
Please keep in mind:
Only your friends can add you to groups.
When a friend adds you to a group, you'll get a notification right away.
You can leave a group anytime. To do so, just go to the group page and click "Leave Group" in the right-hand column. Once you leave a group, you can't be added by anyone else unless you explicitly request to be re-added."
Doesn't look like it. I did a quick scan through settings, didn't see a box to check or anything to prevent it.