A passenger snitched on the man sitting close to him after he put his bare feet on the in-flight entertainment screen, leaving dirty toeprints smeared on the screen.
American comedian Andy Richter shared the image on Twitter, which went viral.
Alongside the images, Richter explained how he got the fellow passenger to take his bare feet off the wall.
"So I snitched this f***er out to the flight attendant, who told him to put them down," he wrote.
"Puts them back a few minutes later and I asked him to put them down. 'They're your bare feet, man."
"He was shocked and put them down. When he just put them back up I decided f**k it, I'm tweeting."
"We had to get off the plane because of lightning, and there were dirty toes smudges where his feet were."
"I am not exaggerating. You could see the outline of his big toe, etc."
"The flight attendant came back right before we got off and asked him to take them down again," Richter added.
"Guy did and asked, 'Is that like a just-when-taxiing thing?'
"Attendant: 'No, it's a basic airplane courtesy thing'. Guy seemed surprised to hear that."
Many Twitter users tweeted back to the comedian's post, remarking on the dog underneath the passenger's legs.
"Lol even his dog is judging him," one person replied.
"Poor dog looks grossed out," another added.