When I first moved to the US over eight years ago, I thought it was very odd that people put lids on their take-away coffee. I found it quite strange to drink through a hole in a lid rather than to just drink directly from the cup, and routinely discarded the lids in order to enjoy my beverage the old-fashioned way. I thought it odder still that people would walk and drink their coffee at the same time, but it didn't take long for me to realise that this was a supremely useful activity afforded by the afore-mentioned lids.
The annoying thing was that although the lids generally did a good job of keeping coffee in its place, every so often a small amount of coffee would escape from the cup and drip onto my clothes. And with Murphy's Law in full effect, it typically happened when I had on a clean white shirt. Before a meeting.
Initially I thought it was just random manufacturing defects in the lids, or that the lids weren't on well enough. But one day I investigated further into the drippage and uncovered the culprit: the seam in the cup where the cardboard is joined together. If the lid is placed in such a way that the mouthpiece is more-or-less directly over the cup's seam, chances are that the seal will not be completely air-tight, and when you tilt the cup to take a drink the coffee will drip out of the cup and onto your freshly-laundered shirt. The solution? Simply rotating the lid to ensure the mouthpiece is directly opposite the seam appears to solve the problem – at least it has never happened to me since I started being more vigilant about lid placement.
I've never really thought this was much of a revelation – it seems like common sense, really – but having explained it to two friends recently I decided maybe it's not that obvious after all, and hence this completely non-HD-DVD-related blog post 🙂