Secret burgers

The burger joint 500º at 1504 Sansom St. has started a burger of the week, but it won't be advertised anywhere but on Twitter/Facebook.

Just say the secret word to the cashier, and the cooks make it up for you. It's priced at $8, a premium.

This week's is "STINKY" and gets you a topping of farmhouse cheddar, baby arugula, bacon, and kosher pickle remoulade.