But while some of it can be attributed to being in confined spaces for too long, it's hard to justify others.
Couples doing yoga together in the back row and a passenger reading porn are just some of the weird examples.
So as the year draws to an end, we look at some of the strangest things people have done during a flight:
Flyers are often advised to do stretches while in the air to boost circulation.
Perhaps that's why we've seen so many instances of people doing yoga on flights recently.
But one couple took it to the next level when they started doing yoga poses together.
As well as doing various stretches, the pair were also seen pulling some seriously hardcore lifts.
Reading a porno mag
Sex may be everywhere but looking at porn is another matter.
Earlier this year, one passenger spotted a man reading a porno mag next to him on a morning flight.
As well as flicking through Japanese cartoon porn, the the passenger was also seen looking at pictures of naked women.
Bare feet on tray table
Passenger shaming websites never see a shortage of photos of people sticking their feet on the armrests or even headrests of the seats in front of them.
But one woman was called out for putter her bare feet onto a tray table, she refused to take them down.
The woman had apparently argued that she needed to rest her feet because she had injured it "during ballet practice".
Picking off dead skin from feet
If having someone else's bare feet near you is enough to make you sick, you might want to look away now.
One traveller had the misfortune of being seated next to someone who was picking the dead skin off their feet.
The woman was apparently playing on her phone at the same time, completely oblivious to her revolting actions.
Giving someone else a pedicure
If giving yourself a pedicure on a flight isn't bad enough, giving someone else one seems even more unbelievable.
But one passenger spotted a woman doing just that.
Perhaps even more weirdly, the recipient appeared to be sleeping at the time.
Helping a child to vandalise
One passenger was spotted helping a child vandalise some tray tables just last week.
The unidentified woman was seen guiding the toddler's hand as he scribbled over a whole row of tray tables.
The viral video sparked outrage after it was posted to social media.
Letting a child use the potty in the aisle
View this post on Instagram
PRO TRAVEL PARENTING TIP: Use the lavatory for your child. **BACKSTORY: Parent brings own potty seat on board, sets it in aisle midflight to have child use (in front of everyone)- when discovered by crew was advised she couldn’t do this & would need to utilize the unoccupied lavatory…and her reply…“I don’t give a shit!” [NOTE: obviously not shaming or identifying the child. But this literal shit is happening out there, folks.] #zerofucksgiven #pottiesonplanes #passengershaming #FAIL
In another example of bizarre parental behaviour, a woman was spotted letting her child use the potty in the middle of an aisle.
The woman reportedly said "I don't give a sh*t" when she was asked to use the toilets on the plane instead.
The post on Instagram sparked over a thousand comments with many calling the incident "disgusting".
Adult weeing on the floor
Perhaps even more shocking is a passenger who decided to urinate in the galley of a plane in front of cabin crew.
The woman was seen with her knickers and leggings pulled down, while still using a phone.
The incident reportedly happened while the toilets could not be used as the plane was being refuelled.
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