You throw the dice to see who you'll seat next to on a flight. Unless you're going with two others, you'll likely be seated with a stranger.
Sometimes a passenger is silent and sleeps the entire trip. Sometimes you'll start up a discussion, which might be beneficial or unpleasant.
One lady was astonished by her husband's behaviour on a trip to Florida.
She posted a video of her husband's manoeuvre on @shepherdplayspiano. "I can't believe he did that," she tweets.
The video, captioned "She didn't mind," has over 1.7 million views.
She's right. Given how often people get into fights and get forced off aircraft, it's great to see two people get along.