The awkward act of pretending you don't know anything about a friend or acquaintance's story, even though it's been thoroughly posted about on Facebook, Twitter, Tumblr, etc.
IN REAL LIFE
Girl: So I went to Colorado this weekend with my boyfriend...
Boy (in head): ... yeah, I know. It's plastered all over my damn newsfeed. Looks like I'm about to come down with a case of social amnesia.