Cooties!
Meaning:An imaginary disease caught during childhood by touching a member of the opposite sex. The “cootie shot” must be administered immediately.
Origin
Cooties may be imaginary, but they are highly contagious. "Circle, circle, dot, dot, now you have a cootie shot!" Using your index finger, draw a circle on your arm two times and punch the center twice. You may not know it, but you have just been immunized from a strange disease unique to the United States, cooties. Cooties and cootie "shots" are rituals of American childhood that are transmitted from generation to generation through playground culture. But where did the idea of cooties come from?
The exact origin of cooties is unknown. Wikipedia suggests that the word cooties was derived from the Malay word for biting insect and was used in World War One to refer to body lice. Cooties also might have come from a term with similar meaning, "kutu," used in many Pacific Island languages. Or perhaps cooties entered our vocabulary through an Americanization of the Tagalong word "kuto" of the same meaning, adopted by US soldiers stationed in the Philippines. But the term “cooties” has taken on a life of its own as part of American children's culture.
Made of folded paper, the "cootie catcher" is one name for a popular hand held toy among school children. One surface is blank, the other drawn with dots. The joke is to show the blank side, then run the toy through someone's hair, revealing the dotted surface. It is made so each surface looks the same apart from the "cooties". The device is also sometimes called a fortune teller and used to tell fortunes.

Cooties have spawned not only the cootie "shot” and “catcher” but other children's games as well. Children can compete to build their own insect-like cootie in Milton Bradley's game Cootie. This type of cootie obviously implies a type of bug or louse. But boy or girl cooties are often called boy or girl germs instead. Are they the same thing? No! The four main types of germs are: bacteria, viruses, fungi, and pro