In the past, "four eyes" was a common playground taunt a child might use to insult another child who wore eyeglasses.

In the past, "[four-eyes][1]" was a common playground taunt a child might use to insult another child who wore eyeglasses.

• an offensive way of talking to someone who wears glasses.

(Cambridge Dictionary) [1]: http://dictionary.cambridge.org/dictionary/english/four-eyes