facebook double-take
Person A yells at Person B for being somewhere or doing something. Person B looks like they just got hit by a truck because they didn't tell Person A. Then Person A laughs and says they saw it on Facebook.
'You were at the mall?!' 'What? I didn't tell you that!' 'I saw your face on Facebook, you idiot!'
'You got a tattoo?!' 'What? I didn't say anything!' 'I saw your profile, you dummy!'
'You went to the concert?!' 'What? I didn't tell you!' 'I saw your post on Facebook, you moron!'