Millions of Americans will be taking off for summer vacation destinations to get some rest and relaxation, but sometimes flying the friendly skies can be a headache.

Expedia has just released its annual survey of the travel behaviors that really tick people off.

RELATED: Clark’s secret to finding the cheapest flights possible

These are the worst passengers to fly with…

For the fourth year in a row, more than half of the 18,000 people who responded to the global survey said the passenger who kicks, grabs or bumps their seat is the most annoying.

Perhaps this behavior has become so prevalent since some airlines are decreasing legroom to add more seats.

If you don’t want to spend more money for a premium economy ticket, Expedia says you may still be able to avoid seat kicking by choosing a seat in front of an exit row.

Take a look at the five worst types of passengers to encounter during a flight, according to the survey:

• The Seat Kicker/Bumper/Grabber: 51%
• The Aromatic Passenger: 43%
• The Inattentive Parent: 39%
• Personal Space Violators: 34%
• Audio Insensitive: 29%

Here’s a travel etiquette question for you: Is it okay to go barefoot during a flight? Over 90% of global respondents told Expedia that it’s just not acceptable.

We put that question to Clark’s Twitter followers and got this response:

Expedia says getting comfortable on a long flight is difficult, but there’s a happy medium to avoid grossing out your fellow passengers — so only remove shoes and never prop feet up on the seatback.

The survey found that most passengers just want peace and quiet during flights. More than 75% of Americans dread sitting next to someone who talks too much.

Want a more restful ride? Here are the quietest seats on an airplane, according to a pilot.

More Clark.com travel stories:

• The best day of the week to book a cheap flight
• Clark Howard warns about American, Delta and United’s cheap fares
• Southwest vs. JetBlue vs. Alaska: Which airline is best?