Lost in Translation
"Tack" in Swedish means both "please" and "thank you." (I mean that you say "tack" when you respond in the affirmative as well as in the negative, as in 'ja, tack' or 'nej, tack.')
Last summer, I spent a few weeks visiting a colleague who lives outside of Dębica, in the Carpathian mountains, an hour and a half by train from Krakow. Given both the low price and readily available supply of alcohol, my personal liquor consumption reached some sort of an all-time high.
Nonetheless, there was no way I was going to be outdrinking the Poles, and both my head and my liver were glad that I didn't even try. I learned that lesson after an ill-fated rendezvous with a bottle of Tequila in Mexico. In fact, I stopped drinking rather early in the evening, about the time that the walls began to spin, and my host appeared to have sprouted an extra head.
However, there seems to be an unwritten rule in Poland, that if a shot glass is empty, it must be filled up. And Swedish is my default foreign language, so if we're not speaking English, it is just as likely as not that Swedish (rather than a poor attempt at the local language) will automatically come out.
"Do you want something more to drink?" asked my host.
To which I replied, "Nej, tack."
I meant to say, "No, thank you," but he heard it as, "No, yes" and decided to fill up my shot glass, just to be on the safe side. After all, you don't want any thirsty (or sober) guests on your hands.
Needless to say, the memory of the rest of the evening is blurry at best.