Here we go again.

Here come the crowds, the long lines, the triple-digit heat — and here come the attitudes.

"People are frustrated," says Diane Gottsman, an etiquette expert and the owner of The Protocol School of Texas. "There's cramped seating, long layovers and then, when you throw in an entitled passenger, it's like a toxin. It spreads negativity throughout the plane."

This summer travel season promises to be all about that. Maybe we don't vacation enough (two in five Americans fail to claim all of their vacation time). Maybe it's the too-good-to-be-true offers associated with seasonal travel. Then again, maybe it's a reflection of a presidential campaign running heavily on attitude.

But here we are, about to start the summer of entitlement. Everyone from your seatmate to your restaurant server is suffering from these me-first issues, but you don't have to join the crowd. You can check your attitude at the front door and still enjoy your trip.

Entitled traveler incidents are becoming so common, it's hard to know where to begin. Let's start with Patricia Fallon, a nurse from Mount Prospect, Ill. On a recent American Airlines flight from Chicago to Cabo San Lucas, Mexico, she found herself seated close to a college football team. The men believed they were entitled to unlimited drinks — specifically, mini-bottles of Jack Daniel's — which they sucked down, sometimes two at a time.

"Their behavior quickly turned raucous," she says. When she turned back, she saw the bottles lined up on their tray tables. They began to scream and spew expletives. The crew did nothing to stop them. Instead, she says the attendants fanned their alcohol-fueled tirade with even more bottles of booze.

Fallon asked for a full refund of her tickets from the airlines, arguing that she deserved a quiet flight. American denied her request, but after she sent an email to an airline executive, it offered her a $100 voucher and an apology.

Actually, airlines want you to believe you're entitled to something, but only if it's in their interests. Like short security lines. In fact, Airlines for America, the industry's trade group, launched a website called iHateTheWait.com just before the busy summer travel season. It wants to encourage you to post photos of the unusually long lines on Twitter and Instagram (don't forget the hashtag #iHateTheWait) in an effort to shame the Transportation Security Administration into adding staff.

The issue of entitlement also came up after a recent column I wrote about aggressive solicitation for tips. Restaurant workers who responded were outraged that anyone would assert that the price on your bill could be the price you actually pay.  Instead, they argued that because the law allows their employer to pay them below minimum wage, they were entitled to a tip.

"Tipping is part of the total cost," wrote Jack Lyons. "Don't go out if you can't afford it."

Lyons then called me an expletive that can't be published here. By definition, a tip isn't mandatory; if it were, then it would be included in your bill. The only part of the check you have to pay is listed under "total." You can pay more if you want to — and many hard workers in jobs that depend on tips deserve generous ones — but by the law you don't have to.

Gottsman, the etiquette expert, says while it's polite to leave a gratuity in the United States, Lyons lost the argument when he started name-calling. Entitlement leads to aggressive behavior, and there's more than negativity that ripples from that attitude. Entitlement takes away your credibility and makes your fellow passenger or your customer far less likely to help you.

"Entitlement," Gottsman adds, "doesn't travel well."

Lose the entitlement

• Adjust your expectations. You're not entitled to a short security line. It's nice when it happens, and you should be grateful when it does.

• Avoid other entitleds. Stay away from sites that promote an entitled attitude, such as passenger shaming sites or blogs that promote entitled behavior. "Watch what you say in person and in social media," adds Gottsman, the etiquette expert.

• Learn to say "no." Whether it's an overbearing service employee or a fellow passenger insisting that you switch seats, you have to set boundaries and learn to say "no." The only way to stop the entitled attitude is to politely but firmly challenge it and refuse to comply.

Christopher Elliott is a consumer advocate and editor at large for National Geographic Traveler. Contact him at chris@elliott.org or visit elliott.org.