My comment to Kenny inspired me to list snappy one-liners that refer to a specific institution in a city, but have now taken on a life of their own, to define the city. After the first few, inspiration dried at the rate of the Aral sea.
1. London: Mind the Gap
2. Bangkok: Same same but different
3. Mumbai- Yeh hai Bambai meri jaan
4. Delhi- Chalo Dilli!