Got your finger up your nose? (We hope not!) If you do, you can probably feel a booger. Boogers are made of dried mucus, dust, pollen, and dirt. They can be squishy or hard, but they do an important job — they help keep that bad stuff from getting into your lungs. Boogers are full of germs, so it's a good idea not to pick them (blow them out into a tissue instead).