The nose always needs to be clammy to protect the health. If you breath in through the nose, there are often tiny particles which make their way inside your nose. Mostly those particles don’t get too far, because they are filtered and stick in your nose hairs and your nose-slime – which is good. Imagine every particle would make its way through the nose into your body. Thats why you can get ill when your nose is too dry! But lets return to the main question: how do boogers occur? Well remember those particles? Well they keep stuck in your nose, mixed and covered in slime. And with each breath more particles enter your nose and anytime they attach to the already stucked one which ends in a snowball effect. The booger grows! Well and when you snot or sneeze, you can see it in the blorag. Believe it or not – its a fact that little children eat their boogers by nature and its (don’t laugh) healthy to build the immune-system.