As airlines button up dress codes, these clothes will get you kicked off a flight

Air travel has certainly changed over time, and an occasion that once mandated dressing smartly has become considerably more casual. 

Now, customers on Spirit Airlines are subject to being removed from flights if they are "barefoot or inadequately clothed (i.e., see-through clothing; not adequately covered; exposed breasts, buttocks, or other private parts), or whose clothing or article, including body art, is lewd, obscene or offensive in nature." 

Here are some other rules that airlines have regarding clothing. 

Shorts are fine, but "speedos and bikini bottoms are not allowed," said Hawaiian Airlines. And bare feet are not OK either.

"In all cases, clothing must not be lewd, obscene or patently offensive to others," said Hawaiian Airlines. 

Southwest Airlines passengers cannot wear clothes that are "lewd, obscene or patently offensive," and passengers must wear shoes. 

Similarly to Southwest, passengers on United have a pretty loose dress code. 

United Airlines' contract of carriage specifies that passengers must be "properly clothed." 

Clothing cannot be "lewd, obscene or offensive" as well - and passengers have to wear shoes. 

Delta's code of carriage does not have a specific dress code.

It does state that passengers can be removed when their "conduct, attire, hygiene or odor creates an unreasonable risk of offense or annoyance to other passengers." 

Qatar Airways has a dress code for passengers in business class and above, says its website. 

"Depending on your destination, there are different rules and regulations regarding the type of clothing you should wear. The dress code is designed to ensure passengers' comfort and safety while traveling, so it is important to understand the rules before departing," said Qatar Airways. 

This dress code prohibits shorts, sportswear and "overly revealing clothing," and business class passengers should be dressed "smart casual." 

"Passengers should pay attention to the dress code when traveling in business class, as it will ensure their comfort and respect for other passengers," said Qatar Airways.