I know that this cartoon is difficult to read, but the main idea is pretty straight forward, so you don't really have to be able to read the captions. It is a commentary on the different blood types, and how the personalities interact.
As you can see, if told not to cross an arbitrary line, Type A will absolutely not cross.
Type B will hop across the line while the teacher is still talking.
Type O will sneak across the line when the teacher is not looking and...
Type AB will keep an eye on the other kids, and then rat everyone out when the teacher returns.