I cringe when the duty-free pitch starts at 35,000 feet, but according to a new study by HSBC, it’s the highlight of the flight for many travelers. HSBC polled thousands of flyers and found that Americans spend an average of $51.32 on in-flight purchases each time they fly, with the bulk of that splurge going to duty-free purchases ($32.53). Other top expenditures were for onboard Wi-Fi ($4.92), food ($11.68), drinks ($4.56), and alcoholic drinks ($4.76).

Better watch how many of those in-flight alcoholic drinks you’re buying: The survey also polled flyers on the most annoying in-flight behavior, and “people who drink too much” was irritating to 44 percent of respondents. Other onboard irritants include being rude to flight attendants, parents who let their children kick the seat in front of them, taking off smelly shoes, parents who allow children to “run riot,” reclining without asking, and stuffing the overhead bins.

Super excited that your flight arrived safely? Keep it to yourself and stay seated—15 percent of people polled hated passengers who clap when the plane touches down, while 36 percent were annoyed by people who stand up immediately after landing.

If you want to blend in while flying, 40 percent of the people surveyed said that they wear jeans and a T-shirt while flying. (Which sounds cold to me—pack a sweater!)

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