Walking from the hostel to the supermarket involved crossing two streets. I had read a lot about crossing streets in Vietnam, but as usual reality was something else entirely. With streets in Saigon, the concept of a 'lane' doesn't really make sense. It would be much more helpful to think in terms of water: about half the street's width flows in one direction, the other half in the other direction. The only difference being that the flow doesn't consist of water molecules, but of motorbikes.
To continue the water analogy, you can't wait for any gaps when trying to cross the street: there never are any. Instead, like when you cross a river, you just start walking and hope that the flood of motorbikes will flow around you.
Standing on the side of a street and knowing that all you have to do is start walking, it is quite terrifying to look into the oncoming traffic. But once you start moving, as long as you walk confidently at a single speed in a single direction, it's not bad at all - somehow the drivers know just how to avoid you. Fascinating!
