Udder
Before 1950 it was still frequent and cheap sustenance, then it is somewhat fallen into disuse, in order to resurface nowadays as a delicacy in some restaurants
In Antwerp and Rotterdam would still be butchers that sell udder. (Something for cities?) Elsewhere it can sometimes be obtained on demand. The udder is usually already cleaned and cooked. Udder cooking is specialized work. It happens in broth and lasts an hour or five.

Udder is a soft fabric with a sponge -like structure. A fresh udder has long been kneaded and flushed. Quiet a work, needs a lot of time. Then the udder is cooked one day (or night) (on the stove) on a low heat. You may want to put some bones on the bottom of the kettle, then the meat is not sticking.
Then you can cut the udder into slices to fry tasty spiced. At home, the sliches were breaded.

At the British court the supplier in the 18th century took the intestines of cattle after slaughter. For udder was explicitly made ​​an exception. Who had to stay!
To author Louis Paul Boon udder was so good that he devoted in his ”Food on Flemish ' (1972) two chapters on it.

Like uterus and testicles sows udder was a delicacy among the Romans. For this, gestating and lactating sows were even slaughtered. According to Pliny the udder tastes best when the sow had given birth 2 to 3 times, and was killed one day after the birth (‘before the piglets have been drinking'). The long udder was rolled up and fixed impaled.


Testicles

Meatballs or rather real?

The culinary term for the testicles of animals in the United States is fries, or (Rocky) mountain - or prairie oysters. In France they are called animelles. Here sometimes white kidney.
Serbian chef Ljubomir Erovic published a cookbook with some exclusive fucking dishes.

Remove the balls from the bag, rinse them well, and boil them in salt water.
You can them bake or fry them, possibly sliced ​​or beaten flat (then they are less recognizable).

Of liver and to a lesser extent kidneys can be said that they have a special and distinctive flavor. Udder and testes is much less pronounced. Especially the texture betrayals that it is not about muscle. They do not have a distinctive flavor. But meatballs taste certainly no balls.

Eyes

Eyes are edible. In various cultures. And in some TV programs.
I have never let my eyes on eyes. Maybe because I do not like being stared at while eating. (That's rude.) And I have trouble to look my food straight in the eyes.
Although I like to try new and strange things I never for a moment thought of eating eyes. The idea does not excite me to experiment.
But do not let that deter you to push your own horizons and boundaries.
If you want so you can keep an eye on your fork.