The map is not the territory.
He meant that a map gives you an idea of how the terrain, streets, countryside, etc. might look, but a map is NOT the real place.
Likewise, I would suggest that numbers are not reality, they are a way to represent the things we see, but in and of themselves numbers are NOT real. They don't lie or tell the truth. They are not animate objects with a sense of morality. We can use them anyway we wish. And we do.
Numbers can be used in a humorous way. Here are some math jokes that might get a laugh from you elementary school mathematicians:
Teacher: How much is half of 8?
Boy in math class: Half down or half across?
Teacher: Down or across? What do you mean?
Boy: Half down gives you 3 and half across is zero.
Why is the number 10 afraid of the number 7? Because 7 ate nine and 10 is next!
What does the zero say to the eight? Nice belt!
What did the 1 say to the 7? Nice visor!
Ok, enough with the math clothing jokes. How about geometry?
What do you get when two geometric figures collide at high speed? A rectangle.
Now onto teaching:
What did the Excel Math Lesson Sheet say to the textbook? Leave me alone, I've got enough problems of my own.
There are three kinds of math teachers in the world. Those who can count, and those who can't.
What's the best time to go to the dentist? Tooth-hurty
What did the Five say to the Two about the Vee? I'd like you to meet my cousin from Rome.
I'd stop at this, but I just found a website dedicated to math stories and jokes used in the Simpson's TV show. You might enjoy it.