Facebook cock block
When someone ruins your chance to chat with a hot girl on Facebook by randomly commenting on your post. You're in the middle of a cool conversation, and then some random person says something dumb and breaks the vibe.
'I like your post!', while you're trying to talk to the girl who just liked your post.
'This is the best post ever!', when you're trying to impress the girl who just commented on it.
'I’m here to ruin your day!', because she’s bad at timing and cock blocking.