Xenophobic, racist joke

A "joke" I received via email:

Subject: The United States of America
A Somali arrives in Minneapolis as a new immigrant to the United States.

He stops the first person he sees walking down the street and says, "Thank you Mr. American for letting me in this country, giving me housing, food stamps, free medical care, and free education!"

The passerby says, "You are mistaken, I am Mexican."

The man goes on and encounters another passerby. "Thank you for having such a beautiful country here in America!"

The person says, "I not American, I Vietnamese."

The new arrival walks further, and the next person he sees he stops, shakes his hand and says, "Thank you for the wonderful America!"

That person puts up his hand and says, "I am from Middle East, I am not American!"

He finally sees a nice lady and asks, "Are you an American?"

She says, "No, I am from Africa!"

Puzzled, he asks her, "Where are all the Americans?"

The African lady checks her watch and says..."Probably at work."

Is this supposed to be funny? I'm sure it's the wit and wisdom of some officebound, ass polisher. You know the type of guy: Degree in business administration, thinks he's real productive and the hardest working among all his co-slugs, but spends most of his day coming up with lame ass jokes, such as this, on company time.