It is unlawful under Title 18 USC Sec 1543 to alter or mutilate a U.S. Passport. Your passport belongs to the U.S. Government, not to you.
It says so right there on page 6 (emphasis mine):
"This passport may not be altered or mutilated in any way. Alteration may make it INVALID, and, if willful, may subject you to prosecution . . . Only authorized officials of the United States or of foreign countries, in connection with official matters, may place stamps or make statements, notations, or additions in this passport. You may amend or update personal information for your own convenience on page 7."
So, do NOT tamper with your passport.
(I would argue that this law also prohibits microwaving or pounding the new e-passports to disable the RFID chip, as some FTers have spoken about doing to reduce the risk of identity theft.)