face-dusting
Face-dusting is when you post a stupid, salty comment on your friend's Facebook and then vanish like a fart in a hurricane. You don't care if they cry or get mad. You just want to be the annoying kid in the back of the bus.
Your friend posted a picture of their new dog. You comment, 'That dog looks like it was hit by a truck.'
Your friend's ex posted a status about how happy they are. You reply, 'Still got the same face as when you broke up.'
Your friend posted a selfie with a new haircut. You write, 'This looks like a raccoon got a perm.'