Yesterday an obscene photo appeared in my Facebook newsfeed because a friend was "tagged" in it. The photo had been posted on the Facebook page of a complete stranger whose account had been hacked. The hacker then "tagged" the photo to my friend and three other people. It appeared in the timeline of all five people targeted by the... hacker *and* the newsfeeds of all their friends.
The photo included full frontal nudity of a middle-aged man. He may be the 6th victim *or* the perpetrator. Who knows. In any case, it is an image either of my children easily could have been exposed to had they been sitting nearby. Fortunately they weren't as I'm not quite sure I could even begin to explain to them what he was doing or why someone would take a photo of that.
The way to check your settings is to click on the small triangle at the top of the page (to the right of the lock symbol). Click on "Settings", then "Timeline and Tagging". In the section in the middle of the page labelled, "How can I manage tags people add and tagging suggestions?", I recommend changing the "Review tags people add to your own posts before the tags appear on Facebook?" and "Review posts that friends tag you in before they appear on your Timeline?" to "On". You may want to adjust some of the other settings on that page as well.