Note from  The Fiddler's Companion:

"FOUR POSTER BED, THE.  AKA and see "Four Corners of St. Malo," "Four Corners Reel," "Four Posts of the Bed," "Les Quatre Coins du Lit," "Les Quat' Coins de St Malo." English, Scottish, Irish, Shetlands; Polka, Reel or 'Programme Piece'.  Ireland, Donegal. D Major. Standard. ABB (Phillips): AABB (Martin).  This tune's 'B' part dramatizes the four poster bed by giving four taps with the frog-end of the bow on each of the four quarters of the belly of the fiddle, interspersed by a right-hand pizzicato.  The melody is popular in the Shetlands, though probably not of Shetland origin admits Cooke.  On an early recording made for Comhaltas, Donegal fiddler John Doherty relates the story of "The Fours Posts of the Bed" and then plays the tune.  His story tells of an itinerant fiddle player who finds refuge for the night in a cottage which lacks a bed for him.  Not wanting to be inhospitable, the man of the house fashions a bed, and in return the fiddler composes a tune to thank him.  Under the title "The Four Corners of St. Malo" the melody was recorded for Philo by French-Canadian fiddler Henri Landry.  As has been noted by any fiddler who attempts to play this tune in the traditional manner, tapping the metal end of the frog on the belly of the violin often produces nicks and dings in the wood.  To prevent this damage fiddlers in Donegal shout in Gaelic "Aon, do, tri, ceathair" (one, two, three, four) as the tap the four corners of the violin with their bow in the vertical but with the fleshy part of their middle finger covering the end of the frog."

I had a phase of playing this one some years ago, and with a little practice was able to tap the bow on a nearby table instead of on the fiddle; the pizzicato bit can just as easily be done with the left hand.

Malcolm