Cooties

It is used in the United States, Canada, Australia, New Zealand, and the Philippines as a rejection term and an infection tag game (such as Humans vs. Zombies).

The earliest recorded uses of the term in English are by British soldiers during the First World War to refer to lice that proliferated in battlefield trenches.

[4][9] Like the British 'dreaded lurgi', the cooties games developed during the early 1950s polio epidemic, and became associated with dirt and contagion.

[1][10] The lice of the First World War trenches nicknamed "cooties" were also known as "arithmetic bugs" because "they added to our troubles, subtracted from our pleasures, divided our attention, and multiplied like hell.

Often the "infected" person is someone who is perceived as different, due to disability, shyness, being of the opposite sex, or having peculiar mannerisms.