There are more bicycles than people in Amsterdam and every walk around the city centre is accompanied by the sound of their bells. As a professor told us at his speech today, every bell means 120 kilos of destruction machine (100 kilo Dutchie + 20 kilo bike). You have three options if you hear such a bell while walking on a bicycle path: fight, flight or freeze. Fight is probably not the best option given that they drive around with speeds of up to 20 km/h. Flight is also difficult, especially when you are from a country with left-hand traffic. Therefore the best option would be freeze so that the destruction machine can peacefully pass by.
On the photo you can see a very peaceful version with a bunch of flowers.