A restaurant in Memphis serves burgers that have been fried in 98-year-old cooking grease.

Dyer's Burgers is located in on historic Beale Street in downtown Memphis, Tennessee. Their claim to fame is that their burgers are fried in the same cooking grease that has always been on the eatery's grill! They strain the grease on a daily basis, but they never throw it out, so the odds are good that customers are eating burgers cooked in grease that is several decades old!
(Source: 1, 2)