4 Eyes
The Lovin' Spoonful Lyrics

Four eyes, what you gonna do now ?
What will you do now that you wear glasses and have to deal with the social stigma that comes with it?

Four eyes and how much do you see now ?
How much has your vision improved with the help of your glasses?

How many fingers? Ha ha ha.
A sarcastic response to being asked how many fingers someone is holding up, implying that poor eyesight is a source of embarrassment and shame.

When your kids that see through plastic with a harness of elastic
Refers to the experience of having to wear glasses as a child, which often involve plastic lenses held in place by elastic bands.

So the girls all think you're icky and the boys all think you're queer
Society tends to make fun of boys who wear glasses, calling them names and making them feel bad about themselves.

Then the hinges all get rusty and the seventh pair gets busted
The experience of having to replace glasses frequently, as they become worn out, broken or outdated.

So you graduate to tortoise shell that makes you look severe.
As a teenager, you might opt for a more mature and fashionable style of glasses, such as tortoise shell frames.

When you're so blind they call you Batman, you can't even see a fat man
When your vision is so poor that you can hardly see anything at all, people might compare you to the visually-impaired superhero Batman.

You can't dig just where he's at man without windows on your eyes
It's difficult to know what's going on around you when you can't see properly, cannot distinguish between objects or people depending on their distance as glasses allow.

But the frames ain't your decision and they're fitted with precision
Even though you might not have a say in the design of your glasses, they are made to fit you perfectly to improve your vision as much as possible.

And they magnify your eyes like they're a pair of cherry pies.
Glasses have the ability to magnify your eyes, which can make them appear much larger, like a pair of round and shiny pies.

Here's a word to all you parents, give a break to little Clarence
Parents should have sympathy for their child (in this case named Clarence) who may be struggling with poor vision and the need to wear glasses.

When he says the blackboard's fadin' and the world's a fuzzy place
Children with poor eyesight will often complain of not being able to read what's written on the blackboard or seeing a clear image of the world around them.

Mister up in middle classes
Refers to an imaginary, judgmental individual who looks down on people of lower social classes for wearing glasses.

And, please, recall that after all he wears them on his face.
Please remember that glasses are a necessary medical device that people must wear to improve their vision, not something to be ashamed of or embarrassed about.