Airlines are generally pretty liberal when it comes to acceptable in-cabin entertainment, but there are limits. “I have had to ask passengers to turn off porn,” says Heather Poole, a flight attendant and author of Cruising Attitude: Tales of Crashpads, Crew Drama, and Crazy Passengers at 35,000 Feet. If you’re unsure what’s appropriate, her advice: “Pretend you’re in church with your mother, and you probably won’t go wrong.”