Bill Cosby Mum on Rape Allegations During Interview

11/15/2014 9:09 AM PST

Bill Cosby -- Mum on Rape Allegations During Interview

Bill Cosby clearly felt he did not sign up to talk about the recirculated rape allegations when he went on NPR ... because he went radio silent in the most awkward of ways.

Cosby went on NPR during an interview recorded last week -- and all was fine, until the painfully apologetic interviewer asked about the old rape allegations that resurfaced.

The interviewer says, "This question gives me no pleasure, but there have been serious allegations raised about you in recent days."  Interesting that the interviewer expressed such embarrassment.

Things instantly turned silent ...  Cosby wouldn't say another word.  You gotta hear it.  Incredibly awkward.

As we previously reported ... Comedian Hannibal Buress called Cosby out last month during a stand up set -- wondering if people remembered Bill had been accused of rape by 13 women over the years.