Foursquare has had over 400 million check-ins over the last year, and taking a closer look at the data behind them can lead to some interesting insight. For example, Foursquare's engineers used check-in data to determine the rudest cities, based on the number of curse words used in check-ins.
The mechanics behind the data are a bit complicated, but the end results are interesting. Topping the list: Manchester, UK, followed closely by El Paso, TX.
I'm not convinced that this data dictates the rudest cities; it just shows which cities swear the most. But I find the ability to pull this sort of user-supplied information from check-in data fascinating; I'd like to see Foursquare data similar to the regional Twitter accent data. Other cities high on the list include Pittsburgh, Bloomington, IN (home of Indiana University), and both Tempe and Scottsdale, AZ.