A teacher and a student. A teacher is teaching a class and she sees that Johnny isn't paying attention, so she asks him, ""If there are three ducks sitting on a fence, and you shoot one, how many are left?"" Johnny says, ""None."" The teacher asks, ""Why?"" Johnny says, ""Because the shot scared them all off."" The teacher says, ""No, two, but I like how you're thinking."" Johnny asks the teacher, ""If you see three women walking out of an ice cream parlor, one is licking her ice cream, one is s…