I don't know whether that's the song's proper title or not. I heard it years ago by the Clancy Brothers & Tommy Makem. Starts out something along the lines of:

Whatever you say, say nothing
When you talk about you know what
For if you know who should hear you
You know what you'll get
They'll take you off to you know where
For you wouldn't know how long
So for you know who's sake
Don't let anyone hear you singin' this song

Written by Tommy Sands, perhaps?

SDShad (Chris)