The parody which fuzzy and blue relates is hardly particular to one school - that version was well known in my elementary school, although our line 2 was phrased differently, and an informal survey of my dormmates indicates that the majority of students who went to American public schools encountered some version during their schooling. In my school, at least, singing of this version was disapproved but not actively punished - I imagine out of apathy, as the teachers realized that no force in the world can separate third graders from the vulgarity they rejoice in. I think they had the right idea, but for the wrong reasons. The simple fact of the matter is that as a patriotic ode, this version is far superior to Guthrie's.

Look at the lyrics of the "official" version. The message of the song seems to be a bright-eyed "America is a place where Americans can live!" (and if you include the "forgotten" verses, add an "...or is it?"). Okay, fair enough. And Germany is a place where Germans can live. So what? It doesn't exactly shout "America!", which is, after all, the point. Now look at the "bootleg" version. At first, it may seem like an assertion of territoriality, xenophobia, and brutishness, but if we inspect the lyrics closely, we find they are actually a fitting ode to American spirit and tradition.

This land is my land, it isn't your land
This speaks to the strong American tradition of private property. As all of what is now America was once a frontier, at least from the perspective of the settlers who created most of American culture, most of it was at one point turned over to private hands as an incentive, either through charter, land grant, or homesteading. America had no tradition of feudalism, and lacked the strong tradition of common land that necessitated the Enclosure Movement in Europe. In contrast with Europe, communist and socialist movements never gained much purchase in America, and while pockets of communitarian influence have arisen from time to time throughout American history, they have never become a significant influence. The 5th Amendment of the US Constitution requires "due process" and "just compensation" for property to be taken for public use, and even this power is still under challenge, with some seeking to further restrain the power of eminent domain. Meanwhile, privatization and deregulation movements urge the transfer of property currently under control of the state to private hands.
I got a shotgun, and you don't got one
One could argue that this line constitutes a reference to the Second Amendment of the Constitution - Americans, empowered by the private ownership of weapons, are able to defend their land from forces both foreign and domestic. Of course, the point of the amendment is that an armed populace could resist an oppressive regime that would obviously have weapons of its own - "I got a shotgun because you got one". Further, some would argue (and argue, and argue) that the introduction of mechanized warfare and the enactment of restrictions on private gun ownership makes the whole thing a little silly - "I got a shotgun (with a magazine of not more than five rounds), and you got a M1-A1 Abrams".

However, patriotic songs are usually allowed a little inaccuracy and anachronism - we've pretty much finished the task of "a thoroughfare for freedom beat[ing] across the wilderness", and I would use neither the words "alabaster" nor "gleam" in describing our cities, but America the Beautiful is still sung.

If you don't get off, I'll blow your head off
This line refers to the vigor with which Americans have taken up arms to defend their property and freedoms, both in repelling foreign attackers, as in the War of 1812 and the early phases of American involvement in World War II, and in opposing tyranny at home. From its creation with the American Revolution, with Shay's Rebellion and the Whiskey Rebellion soon after, to the Civil War and the modern militia movement, with thousands of rebellions, insurrections, skirmishes, and subversive movements in between, Americans have been fairly quick to take action when they feel that their government has become too overbearing. Of course, these campaigns have a record of success that might charitably be described as "mixed", but for our purposes, what's important is the spirit with which they are undertaken.
This land is private property.
This line restates the themes of the first line, and with its stark, standoffish tone, echoes the resolve of the third, all with a tidy conclusion to the rhyme. All in all, far more appropriate and far more inspiring than the soft-focus, geography-fetishizing tribute to inclusiveness that is the original.