A loyal reader recently pointed out to me that no joke has ever been improved by telling people beforehand how funny it is. Hence we're dropping 'Friday funny' as the name for our regular end-of-the-week diversion, and going with 'Knock-off time'. We thought of 'Quitting time', but much as we appreciate our many North American readers, this is an Australian site.

We began this week with Hugh Jorgensen coining the phrase 'RAT pack' to denote the 'troika' of nations (Russia, Australia and Turkey) that will head the G20 in 2014. So in Hugh's honour, here's an amazing performance from a real Rat Pack member, Sammy Davis Jnr, who does some uncanny impersonations of his contemporaries. The whole thing is astonishingly good, but the Dean Martin impression ('Psst, which way's the audience, pally?') is a highlight.

And given the commemorations for Martin Luther King's 'I have a dream' speech in Washington this week, Sammy Davis Jnr's opening stage banter is also notable.