Informant is my friend that has grown up in Taiwan and Canada, while also studying in LA.
狗屎運 (Gou Shi Yun) literally means: “dog poo luck”. In our culture upon stepping on any type of poop is considered good luck. We just happen to say dog poo because there are more stray dogs that poo on the streets. Stepping on the dog poop on the street is in itself an unlucky event, but doing so is supposed to bring some personal good luck. Walking around carrying the luck everywhere as you go around!
I personally think that this is a pretty funny superstition about stepping on dog poop. It is like feeling bad for yourself to be this unlucky to step on poop, but thinking of it bringing good luck to yourself is a good way to get around being sad for oneself.