Facebook Familiarity
When you think you know someone but it turns out you've just seen them on Facebook. Either through a friend or by sneaking a peek at their profile because you're a Facebook stalker.
'You're the guy who liked my post about my cat dying.' 'No, I liked your post about your cat dying.'
'I've been friends with you since 2013 but I don't remember you.'
'You're the one who stalked me on Facebook.' 'No, you stalked me on Facebook.'