...when you carry a book with you, so if you find yourself sitting in a public place you can look like your reading so you don't have to interact with anyone, but then get stressed about how often you should turn the pages to make it look like your really reading in case someone is watching you for an extended peiod. So you decide you'll have to really read the pages or someone might suspect your looking at a book without reading, which would just be weird, so you read the pages to find you forgot to listen to the words, so you have to read it again, but then you've been on the page too long, so you need to turn it mid way reading it the second time....