I always thought that the Grace before sitting down, could set the trend for the inevitable banter during the meal. However it often required a 'certain type' of padre to give it or someone with a natural flair who could make an amusing and appropriate Grace.
The best I think I heard, was when my wife (Mrs Old Duffer) was stationed at Cottesmore - the Grace was delivered by a Luftwaffe officer, in full highland rig and a scots accent at the start of a Burns Night Dinner; I don't remember the words but it brought the house down and set the tone for a fabulous evening.
Old Duffer