When one of your Facebook friends randomly posts "What's on your mind?" as their status. That happens to be the default comment when you share a comment.
Guilty Party: What's on your mind?
Confused Friend 1: Neil Diamond
Confused Friend 2: Happy Anniversary!
Confused Friend 3: More cowbell?
Guilty Party: I think I just pocket Facebooked
You: Dude, sounds more like you Buttbooked us