Beyoncé and JAY-Z have announced a new contest offering fans the chance to win a lifetime's supply of concert tickets — on the condition they adopt a vegan diet.

The Greenprint project was unveiled on Bey's Instagram account yesterday. It states that contestants must promise to eat “two plant-based meals a day” or practice "meatless Mondays" to qualify.

This isn't the first time Beyoncé and JAY-Z have advocated veganism. Earlier this month, the pair co-authored an introduction to Marco Borges' new book The Greenprint: Plant-Based Diet, Best Body, Better World. 

“Having children has changed our lives more than anything else,” they wrote. “We used to think of health as a diet — some worked for us, some didn’t. Once we looked at health as the truth, instead of a diet, it became a mission for us to share that truth and lifestyle with as many people as possible.”