Andrea (from the UK via Cessnock) taught me this one (she learned it from a fellow backpacker), which I found repeated in the Switzerland section of the Lonely Planet Central Europe volume.
When drinking, always wait until everyone has their drink and toast each of your companions, looking them in the eye and clinking glasses. Drinking before the toast is unforgivable and will lead to seven years of bad sex, according to the superstition.
Hmmm. That would explain a great many things…since I dun drink as much as I used to!!!
Musings of a Food and Travel Addict