To help give customers a friendly reminder about appropriate onboard behavior, San Carlos, Calif.’s Caltrain has launched a courtesy campaign on its social media platforms. The campaign, called “Caltrain Manners,” is the result of a recent online survey, where passengers were asked what annoyed them most about their fellow riders. Caltrain tallied the results to determine the three worst passenger gaffes.

Last Wednesday, Caltrain’s social media team posted a humorous GIF depicting the third-most egregious passenger mistake — placing a personal bag on an empty seat. As the post notes, some trains operate at 120% capacity, so every seat is cherished and should be reserved for people, not possessions.

Does that bag have a ticket? The #3 most-irksome #CaltrainManners fail is bags on seats!! pic.twitter.com/CAkLw6tlAZ

— Caltrain (@Caltrain) October 12, 2016

The campaign struck a chord with passengers, who have sounded off on the comments section in Facebook.

“I get if it is an empty train, but if the train is packed... it’s a real jerk move!” wrote one commenter. “At the end of a long day everyone just wants to go home, and for some of us with bad joints (me) being able to sit is real nice!”

“No one should ever have to ask anyone to move anything off the seats,” wrote another commenter. “People need to have a little class and show a little respect. If you didn't pay for two seats, you have no right or proper expectation to occupy two seats.”

“Common courtesy, like common sense, isn't so common,” said one passenger. “When I see the crowd building I take my stuff off the seat next to me so others can sit down. And I'm still old-school enough to give up my seat to someone who needs to be seated more than I do.”

Caltrain posted another GIF on Wednesday illustrating the second-most annoying faux pas, as determined by passengers. The following week will showcase the problem that passengers find the most bothersome.

"I'm on a train. NO, I'M ON A TRAIN!!!"

The #2 most abrasive #CaltrainManners fail is Loud Cell Phone Talkers. Keep 'em short & quiet! pic.twitter.com/cPrN5ACygj

— Caltrain (@Caltrain) October 19, 2016

For updates on the campaign, customers can visit the Caltrain Manners site here, or check out Caltrain’s Facebook page and Twitter account.

Caltrain knows that no passengers are perfect, and everyone makes etiquette mistakes at times. This campaign is just a light-hearted way to remind passengers that all riders are the “public” part of public transportation.