Wit

Almost everyone gets an impression after reading the opening lines of a book. And every author wants to write an opening hook to keep readers coming back.

Trust me, this is getting more important. Now that our attention span is shrinking, readership is losing the battleground from competitors like Instagram, YouTube, and Pinterest.

Fredrik Backman, the Swedish author of My Friends, is one of the best qualified. His book starts with the statement that teenager is the best kind of human. Why is this so? The answer from Fredrik Backman is very simple. Here's how: little children think teenagers are the best humans, and teenagers think teenagers are the best humans, the only people who don't think that teenagers are the best humans are adults. 

Which is obviously because adults are the worst kind of humans.

This is as naughty as knock-knock joke, but it works for readers of all ages.