Jay is the Chinese/Thai word for vegetarian, and from now until October 9th is the annual Ngaan Jay, Vegetarian Festival. To be honest though, it is quite possibly the most innacurately-named festival around. Although everything for sale in Thailand's various Chinese districts during this period is entirely meat free, you'll actually find very few, if any, actual vegetables. Just about everything is either some form of starch (noodles, rice, potatoes) or protein (soy).
In addition to a lack of vegetables, virtually everything is fried:

Another odd aspect of the festival is that Bangkok's entire Chinese community seems to collectively decide that it's not capable of cooking at home during the 10 days, and instead buys every meal 'to go' from a truly remarkable number of street stalls:

Nonetheless, if you're willing to brave the potentially detrimental health risks of the Vegetarian Festival, it's heaps of fun, and in Chinatown, everybody is involved. In Talat Mai, the main market alley, vendors who normally sell meat instead sell soy-based meat substitutes:
If you look closely, you'll see veggie ground pork, veggie scallops, and even veggie pork stomach and intestines!
Across the way, even Nay Uan, normally one of the meatiest stalls around, goes jay, serving up tofu, soy protein and mushrooms in place of pork offal:

Just next door, OK Phat Thai has ditched the epynomous dish and makes a variety of meat-free noodle stir-fries and vegtarian hoy jor:

But my favourite Vegetarian Festival dish is fried yellow wheat noodles, phat mee leuang:

Fried yes, but also one of the only dishes that actually includes vegetables.
