Back in time

Noah and Sarah were good-naturedly teasing each other. I don't remember how it started, but it involved Noah doing something unintelligent and Sarah saying, "Looks like you need to go back to kindergarten." That prompted Noah to say, "Well then, you need to go back to preschool!" Sarah's comeback was, "You need to go back to being a baby!" Determined to have the last word, Noah replied, "You need to go back to your birthmother's uterus!"