You have probably, on a few occasions during that moment of excitement, clicked on what looked like a collectible that you needed. All this collectible was is just a way for spammers to share spam with all your friend's, no priceless rare collectable was even produced and you knew you where just scammed. Worse yet, you posted it and a few other people clicked on share before you could take it off your wall.
Now with FaceBooks new setup, whenever somebody tries to distribute these so called collectibles, it just groups them into their own catagory. So now you may have noticed that the fake collectible messages are non-exsistant now, because since it is not a farmville news feed:
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It will not group itself with the other farmville news feeds, thus, confusing the other facebook users. One way to make sure that a news feed is real is to look in the bottom left hand corner of the message for this icon: 
This icon also helps facebook identify the news feed, and group them together the way they are now. So now when somebody tries to share fake collectibles, it only groups that into one. This is the main reason why you see so many people upset about the facebook grouping. Myself personally, I love it, it makes the games that facebook has to offer much easier to play.
Note: If you do not like seeing the game messages that your friends are playing in the newsfeed, you can block any notices about the games without actually blocking the user. You just simply hold the mouse over your friend's name, click on hide located in the top right hand corner of the message. You will than see a message asking if you would like to hide the user or hide any messages from farmville, fishville, etc...
