One variant of this that I've seen lately is some sort of wrong or easily-disproved assertion or challenge. "Bet you can't name an American city with an E!" or

One variant of this that I've seen lately is some sort of wrong or easily-disproved assertion or challenge. "Bet you can't name an American city with an E!" or "95% of people can't name three European countries. Can you?" It drives engagement not only for people answering the question, but also for those talking about how stupid the post is- either way, it's engagement.