They: "Hey, can you move your bag? I'd like to sit there."
Passenger: "Sure, no problem"
Or, in my case..
They: Stand still and give the smallest glance in my direction
Me: Put my bag on my lap in record time, glance up, smile awkwardly :)

Seriously, I'm guilty as hell of putting my bag next to me in the train. Mainly because I'm not putting it on the floor together with who knows what kind dirt is lying down there. And It's awkward to keep it on my lap if it's not necessary. Of course it's different when it's a busy train.

i mean have you tried politely asking people to move their bags? i'm not gonna sit there with the bag in my lap if there's a spare seat next to me.

Lol, I'll be honest I do this if there are mostly free seats around, the second they start filling up the bag goes between my legs on the floor.

There's nothing wrong with this if there are a bunch of empty seats open. If it's crowded then it's a dick move, but if there's plenty of seats available then there's zero issue.

I put my bag on the seats next to me all the time. Decency is knowing when you need to pick it up and put it on your lap.

I'll move it if there aren't any seats left. If it's practically empty tho, I'd rather not put my shit on the floor. I also would prefer you to sit elsewhere and leave me alone.

Not even kidding, I have done 3/4 of those.

talk about being selfish: not buying a drink for your backpack

I don't put my backpack next to me. It sits on my lap and I hug it. Because I love it. We are one.

I do the third (bottom left) one rather often if I'm at a food court.

Need to print these out and hand them out when someone is doing this on a busy bus ride.

I hug my bag

Personal space bubble

Credit: Anton Gudim: Some of my 4-frames comics on Behance

Well last time i did this with my daki out in the open i got weird looks so of course i gotta put it into my backpack smh

I was under impression that people did that intentionally to reserve the seat for someone. Now reading the comments made me twice as angry

The bus and airport terminals are the two places I do this. Bonus points if you sit the bag down just as someone is coming up to sit in the chair.

Yeah how dare some people rather not go through the public transit equivalent of meeting that guy who singles out the urinal right next to you!