Whisky and water
On a tour of the Glen Moray (shameless plug - you know where to send a crate :) ) distillery, we finished with a taster of the finished product. In actual fact three versions ... an 8 a 12 and a 16 year old dram.
The young - but spectacularly well informed guide - pointed out a little water jug which had some spring water they actually make the whisky from. At this point, one chap, who had been playing the connoisseur commented rather smugly "Glad you have some water for the ladies" (he was an arse). To which the guide, not-quite-as-apologetically-as-he-could-have-been pointed out that professional whisky tasters always put a splash of water into whisky to sample it. Apparently it releases some of the flavouring compounds, thus accenting the nose (smell), and allows the more complex compounds to dissolve, bringing out the more subtle edges of the taste.
So there is a reason.