Harlan, entertained ... Souter, not so much. Two things I enjoyed reading in Nina Totenberg's NPR reports on the Blackmun Papers (available through SCOTUS here). The first one is Blackmun, in his oral history, describing the Justices and clerks viewing pornographic films to determine whether they were obscene:

I remember one time Justice Harlan was there, sitting with his law clerk up front. Of course, his eyesight was almost totally gone, and it was hard for him to see. I sat right behind him, and as the film moved on--and they were all alike // he'd lean over and say to his law clerk, "and what are they doing now?" and the law clerk would describe it and Justice Harlan would say, "You don't say, you don't say."

The second is a written message from Justice David Souter, explaining why he was declining to go to a speech Blackmun recommended:

"I know you get a kick out of these things, but you have to realize that God gave you an element of sociability, and I think he gave you the share otherwise reserved for me."