Commenting or liking friends' statuses from over a month ago. This is usually achieved via facebook's Previous Status Updates feature.
Example of retro-stalking:
Your Friend
Im ready for highschool to be over with!
May 2010
You
ME TOO!!!!
March 2011
Your Friend
Im ready for highschool to be over with!
May 2010
You
ME TOO!!!!
March 2011
by retrostalker April 26, 2011
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