From the Wikipedia article on Nasal mucus:

Mucus dries around the [dust] particle and hardens, somewhat like a pearl forming in an oyster.

I've been referring to pearls as "oyster boogers" since I was a kid. 

Majikthise seems to think abstinance does not work as a means to prevent pregnancy, when actually it works better than condoms.

Condoms work about 85% of the time. A woman can get pregnant even if her partner uses a condom.

Abstinance always works. A woman cannot get pregnant if she does not engage in sexual activity. 

Discovered by accident, DDT became one of the greatest public health tools of the 20th century.

Overuse harmed its efficacy — and made it politically unpopular.

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