"If you're in a White Castle, say 'hell yeah!'" Dennis Coles, a member of the Wu-Tang Clan, bellowed into the mic.
"Hell yeah!" replied the crowd of mostly 20-somethings cramped inside the New York City establishment. Young passers-by pressed their faces against the windows to watch.
"Impossible Burger, turn up!" Coles then said, followed by a bullhorn sound from the DJ behind him.
This was no ordinary evening at the Brooklyn White Castle. Coles - better known by his stage name Ghostface Killah - was performing at a launch party for a plant-based burger by the meatless startup Impossible Foods, which debuted its slider at 140 White Castle locations in New York, New Jersey, and Illinois on Thursday.
For one night only, the rapper, along with fellow Wu-Tang member Cappadonna, famed musician Questlove, and comic Eric Wareheim, turned the White Castle into a club - complete with unlimited Impossible sliders, boozy ice cream, and cocktails made from fountain soda.
White Castle's partnership with Impossible Foods may seem like an unlikely match, since the startup's burger was only available in higher-end restaurants. But the fast-food chain is making a move to attract millennials and teens, two coveted demographics for the fast-food industry.
Other chains, like McDonald's, Burger King, and KFC, have made similar efforts to appeal to younger customers - but to limited success. A growing number of millennials and teens, however, seem to be turning to meat-free, healthier alternatives to traditional fast food, and Impossible Foods is capitalizing on that.
Here's what it was like inside Impossible's wild party at White Castle.