A: You should put away those chips.

B: Why? I'm hungry.

A: You'll leave crumbs everywhere.

B: Someone will pick them up.

A: Probably roaches and vermin.

B: There are no roaches on the bus!

A: That's only because people work to keep things clean.

B: You're exaggerating.

A: There are signs saying no food on the bus.

B: No one takes those signs seriously.

A: Imagine if everyone left crumbs and trash on the bus.

B: I guess I should not make a mess at least.