What is that?

Suddenly I had realized that in many yaoi mangas the main characters are talking about erogenous zones.What thats mean.I knda understand that an erogenous zone is the place where you can feel weak and good if someone touches the plase but anyway its strange can that be possible?Well I knda noticed that i feel strange when someone touches my ears but I am steal confused about this thing.Explain me please ╥﹏╥