Jet2, Ryanair, EasyJet and TUI passengers warned they could be stopped from boarding flights over clothing rule

Summer holiday season is in full flow, with airports set to get even busier once the school holidays hit at the end of July.

But those heading abroad have been warned that they could be in for a shock ahead of their flight.

And it's an issue that concerns the clothes you're wearing to fly overseas.

Most of us dress appropriately when we head to the airport, with our destination of choice dictating whether we're in shorts and flip flops for a break by the beach or got that big coat on for a wintery excursion.

And once those airport pints have been sunk, it's usually about time to get yourself over to your departure gate ready to board your plane.

But it is at this point where you could find your holiday dreams dashed.

Believe it or not, there is such a thing as inappropriate clothing when boarding a plane—and that is with any airline; we're talking Ryanair, TUI, EasyJet, Jet2, British Airways, and so on for those jetting off from UK shores.

And that's not coming from us, but from the experts who fly through the skies as part of cabin crew.

Dress appropriately to reduce the risk of issues (Getty Stock Images)

Speaking to CNN Travel, flight attendant Mary Jo Manzanares opened up on airlines' dress codes and what counts as a major red flag.

She said that passengers may be unaware of the risk that a seemingly harmless slogan on a T-shirt can cause, hence why flight attendants aim to sort any problems before takeoff.

And at the core of any dispute with passengers is prioritising a journey without any outrage.

Manzanares said: "You've got to make your priority resolving things on the ground, making sure that there is no aggression. When you go to 30,000 feet, you may have passenger conversation or banter or inappropriate comments between passengers.

"Add in a little alcohol, and you may be making an unscheduled landing. And no one wants that."

And at the same time, another flight attendant told The Sun that their decision is final.

You could be refused boarding if you don't wear appropriate clothing (Getty Stock Images)

"We're well within our rights to prevent people getting on the flight and it's used frequently for people who aren't dressed in a way we would deem to be acceptable," the anonymous cabin crew member said.

"There are some obvious examples here, including t-shirts with swear words or offensive logos on them, which people are regularly asked to cover up, or remove, before they get on board."

There isn't an official dress code when it comes to airlines, as EasyJet recommends wearing 'loose and comfortable clothing' for your trip.

However, if a member of cabin crew flags there is an issue with your clothing, then you are expected to fix it.

Otherwise, it could well be a case of saying your goodbyes as those you're travelling with fly off and you stay well and truly grounded.

Other items of clothes flagged as potentially being troublesome include swimming costumes, wearing a bikini, and even tops with offensive slogans.

It is also worth remembering where you're travelling too, as not every country has the same cultural norms and clothing rules as Europe.