I know you are, but what am I?

[herbivorie]

"I know you are but what am I?"

I learned that this pharase can be used when a child is bad-mouthed by another child.
I understand that if someone says "You're stupid", the first half of the phrase means "I know you are (stupid)", but I don't understand the latter part.
What does "What am I"? mean?

(I won't use it myself. I just want to understand the meaning.)

 

[Rover_KE]

"I know you are but what am I?"
I learned that this sentence can be used when a child is bad-mouthed by another child.

I don't know where you learnt this, but it's meaningless.

 

[herbivorie]

I don't know where you learnt this, but it's meaningless.

I learned it on the Internet.

In my opinion, for learners of a foreign language, every expression of the language is meaningful, informative, and worth learning.
Also, it helps me understand the culture of native speakers.

 

[Rover_KE]

That is simply not true!

The internet is full of rubbish and misleading information.

 

[SoothingDave]

You are attempting to call me a name. I say that the name applies to you ("I know you are"), and profess ignorance about what you are trying to call me ("but what am I?").

 

[Barb_D]

As Dave says, it's a way that children argue.

The person who is called the rude name pretends that they don't understand. They pretend the rude name is for the person who SAYS it, not the person it is said TO.

Child A: You're ugly.
Child B: I know you are, but what am I. == No, YOU are the one who is ugly. I don't know what you think about me.

It's childish to the extreme. An adult would never use this except as a joke, because adults don't go around saying "You're stupid!" to one another.

 

[SoothingDave]

I guess they never got Pee Wee Herman in Britain.

 

[MikeNewYork]

Perhaps this dialogue is American. We used it when I was a kid. Another one was "I'm rubber; you're glue. What ever you say bounces off me and sticks to you".

 

[bhaisahab]

:shock:

 

[emsr2d2]

None of those mean anything to me so it must be an AmE phrase. I know who Pee Wee Herman is though I don't understand why it's meant to be funny.

 

[MikeNewYork]

I never thought Pee Wee Herman was funny either.

 

[Amigos4]

None of those mean anything to me so it must be an AmE phrase. I know who Pee Wee Herman is though I don't understand why it's meant to be funny.

Ladies and Gentlemen, I proudly present Mr. Pee Wee Herman: "I know you are but what am I?"
Enjoy!

 

[Rover_KE]

OMG! Do people actually laugh at that stuff?

 

[herbivorie]

Thank you to all who kindly answered my question.

I accidentally learned this sentence from the following website when I was searching about another expression:
http://blog.theartofchange.com/pers...ople/what-to-do-if-you-dont-like-being-teased
I think this site is neither rubbish nor misleading. It has actually helped some people as you can see in their comments.