I am 6.5 weeks post-op with silicone sub-muscular implants and they are squeaking horribly -- what's going on?

Your implant(s) sliding against your stretched moist tissues causes a friction rub (sound) that can be felt as well as occasionally heard. This is termed "bourdonnement" and was definitively described in the plastic surgery literature: "Bourdonnement and other benign temporary breast implant sounds." Annals of Plastic Surgery, Vol 43 p589, 1999.

When this occurs after surgery, the sound is related to the incompletely-healed and still-inflamed tissues. The inflammation that causes this sound usually has nothing to do with "a problem" but could indeed be due to overzealous breast manipulation, and typically resolves as tissue heal! And of course, complete healing takes months, so the sound can persist for some time.
Bourdonnement is related to breast implants, but non-implant-related sources of friction rub can be heard on chest auscultation with a stethoscope, and can be associated with a pulmonary embolus from DVT or other sources of inflammation . Bourdonnement alone without any other symptoms (leg pain, swelling, shortness of breath) is NOT worrisome.  

Ibuprofen or Celebrex (prescription) anti-inflammatory medications can be utilized when your surgeon allows this. If you begin to notice firmness or soreness in the "noisy" breast, this could be an early sign of capsular contracture. See your surgeon for evaluation and consideration of a course of Accolate or Singulair and Vitamin E. Best wishes! Dr. Tholen

This can happen! The worst case I have personally encountered in nearly 27 years of high volume implant surgery was a noise like creaking leather (think a horses saddle while riding) when massaging that lasted over two years. It is unlikely this has any consequence, but is aggravating. I don't know how to make this stop.