n. A person who eats a vegan diet before 6:00 PM, and then whatever they want after that.
VB6. No, it's not a tomato cocktail or the latest version of a computer programming language. VB6 is short for Vegan Before 6, the increasingly popular veggie-heavy diet that converts say can do wonders for both the body and the planet.

Coined and devise by food writer Mark Bittman, the regime is pretty self-explanatory: No animal products, processed food or simple carbohydrates during the day. After 6 p.m., anything goes.
—Alexandra Gill, “Tick tock, it's steak o'clock,” The Globe and Mail, May 27, 2009
VB6: Refers to vegetarian or vegan before 6 p.m. Someone who eats meat and in some cases animal products of any sort only with the evening meal.
—Shari Rudavsky, “Meat is off the menu for many seeking path to better health,” The Indianapolis Star, April 30, 2009
2009 (earliest)
You mention here that you had cooked rice on hand. Well, since becoming "VB6", I’ve begun to have many cooked things "on hand". I put 4 pots on the stove at once and fill each with about 1 lb. With dried legumes, or rice or grains. Then into zip lock bags and into the freezer.
—Mats Flemstrom, “What I Had for Breakfast This Morning” (comment), The New York Times, February 18, 2009