There are two things ubiquitous in Vietnam: Motorbikes and Rain. There are something like 4 million motorbikes in Saigon, alone, outnumbering cars by a factor of 9 to 1. Many of the ponchos (like this one) are made with a clear panel in the front so that when you drape it over the front of the motorbike, it doesn't obstruct the headlight. There are even two-man ponchos with to heads built into it for two riders on a motorbike.