I have thought about this topic for quite awhile now and I have come up with a simple way for SOPA to backfire at the U.S. Government if SOPA were to pass in January.
First, we must direct our attention to this URL here: You need to login to view this link
At this page you can submit any petition you would like. Sadly, you must register to do so. After registration, you may submit a petition and it will be published to the website ASAP without any approval.
In the contents of your "petition" you must add lyrics to any copyrighted song you so choose. Since the White House domain is allowing user-submitted content when SOPA is in action, it would make their own domain liable for any content a user submits. Under SOPA, any copyrighted material (even lyrics in word form) shared virtually without the copyright holder's permission would be considered illegal thus forcing the US Government to blacklist or shut-down that domain if the server is within US territory.
By posting a simple song's lyrics to the White House, it is now considered illegal for the site. This will cause a massive backfire on the US Government which may have them go into another discussion about the bill.
TL;DR Posting copyrighted lyrics onto US Government websites will backfire SOPA