This one's too good to wait for tomorrow. I'm not sure where it's from…probably some early Showtime special. It's Don Rickles from Las Vegas with a very odd bunch of guest stars. The song is something Rickles did in his act for years (minus the cameo guests) especially during a period when he seemed to think audiences just wanted to see him sing and dance. The first time I saw him in Vegas, that's pretty much what he did and the talking portions of his stage time were taken up not by insults but by long discourses on how we should all get down on our knees every morning and thank God that he gave us Frank Sinatra. Don later got back more to the kind of thing that had made him famous, like calling people hockey pucks and saying they suck sap out of rubber trees.
You should recognize all of the cameo guests except maybe the guy with the tennis racket. It's Bobby Riggs, the famous tennis hustler who battled (and lost to) Billie Jean King in a vastly overhyped "battle of the sexes" match in 1973. This appearance was probably his sixteenth minute of fame.
The clip runs a little under four and a half minutes. You'll want to play it over and over and over…