Replace "Aggie" with "Hillbilly" and/or "West Virginia", and I've heard these jokes my whole life.
Of course, jokes such as these took on new meaning when I discovered that my paternal grandparents were, in addition to man and wife for a few months short of 60 years, second cousins. Or, to put it another way, my middle and last names are those of two of my great-grandfathers who were themselves first cousins. I'm my own 4th cousin - I commit incest each and every time I masturbate. LOL