They presaged the whack in an earlier show when, IIRC Tony says “...wham, that’s it, you’re gone...” I think they were holidaying at a lake with another couple and the guys got to talking about being on the receiving end of a hit.
If it's the episode I'm thinking of, Tony and his brother-in-law Bobby were talking about what it's like to die. I think Bobby even said something to the effect that it's like turning off a television set - everything just goes dark, which is essentially what happened in that last episode.