A blonde woman is walking down the street, with her blouse open. A cop is approaching from about a block away, thinking, "Boy, my eyes must be going, it looks like that woman's right breast is hanging out."
As he gets closer it becomes apparent that her breast is hanging out. When he gets face to face with her he says, "Ma'am, are you aware I could cite you for indecent exposure?"
She says, "Why, officer?"
"Well, your breast is hanging out."
She looks down and says "OMIGOD, I left the baby on the bus!"