It amuses me to no end that Dan Meyer showed up in Edmonton from California a few years ago and showed us this great graph, which I had never seen before.
It turns out Edmontonians (who love their beer) really spiked the water consumption when they were flushing their toilets during the intermission of the gold medal hockey game at the Vancouver Olympics. (Canada beat the USA, for those keeping score).
I created this notebook file where parts of the graph are obscured and revealed one at a time. A fun exercise in a math class is to project this graph with the information obscured and see how many pieces of information need to be revealed before students figure out what is going on.