Question: What do you do with the hole in a doughnut? Answer: Try to talk about it for a whole minute without repetition, deviation or hesitation - and without coming to blows with fellow panellists! That''s the challenge that has awaited scores of guests on Just a Minute over the years. To celebrate its Silver Jubilee, four of the game''s best known players - Clement Freud, Peter Jones, Derek Nimmo and the irrepressible, not to say uncontrollable, Kenneth Williams - respond to some pretty silly topics with hilarious results in two complete programmes of this much loved radio series. In addition, such talented talkers as Peter Cook, Stephen Fry, Sheila Hancock, Paul Merton and Victoria Wood all add their own unique contributions to the laughter. From ''The Most Extraordinary Person I Ever Met'' and ''My Pet'' to ''Wilhelm Furtwangler'' and ''Burping'', the wicked inventiveness of the panellists is well and truly exercised under the watchful eye of ever-jovial, though constantly embattled, chairman Nicholas Parsons.