Boys and Boogers

My boys are disgusting.

We had a boys weekend last weekend and while we where driving in the car my 4 year old says, "Boogers taste good." Of course I immediately told him no they are not and he should not be eating them. He passionately replied, "Yes they are good. I always eat my boogers. They are good right Jacob." To which my seven year old says, "Yup. I eat em at school when my teacher isn't looking."

What the heck! That is absolutely rude. Why do they do it? And how do I get them to stop?