Gross Domestic Product - GDP

I came across this joke about GDP from today's Nanyang Siang Pau. (Nanyang Business Journal, 南洋商报). The story is roughly like below:

Two economists A & B were paying a visit to their sensei/master who is a well known economist.

On their way, they saw a pile of dogshit on the road. A told B that he was willing to offer B 50 million bucks if B eats the dogshit. Ok B really ate the dogshit and took the 50 million bucks. Then they continued their journey.

After a while, they saw another pile of dogshit again. This time B told A if A eats the dogshit B will return the 50 million bucks to A. A actually a bit regretted giving out his 50 million bucks to B early on and so he took this chance to get back his 50 million bucks by finishing up the dogshit.

Then they continued their journey. After several thoughts they started to realize they actually gained nothing but dogshit in their stomach. They were crying loud, and at that time they had already reached their master's house.

After listening to their stories their master was screaming with excitement: "100 million! 100 million! You two have ust contributed 100 million to our nation's GDP!!! "

Here is the formula of GDP which is taken from Wikipedia:

GDP = private consumption + gross investment + government spending + (exports − imports)

So i think the 100 million bucks from the above story is referring to "private consumption". Hahaha.

I once read about an economist from the United States said that(I could not remember that well) "to grow a nation's GDP (or to boost up a nation's economy), give money to someone to dig a hole on the road, and then offer money to another person to patch the hole up". Hahaha.

Frankly speaking, i think GDP's should be quite reliable else it will not be a universal key indicator to a nation's economic strength.