fendant] asserted his desire to waive the privilege by way of an affidavit which would be impervious to scrutiny or challenge by the [plaintiff]."); Refuse & Envd. Sys., Inc. v. Indus. Servs. of Am., 120 F.R.D. 8, 12 (D. Mass. 1988) ("If defendants wish to retain the right to offer the [privileged] communicati