You can do what you like in the privacy of your own home, but if you go to Shelby's Legendary Shawarma, you had better not ask for ketchup for your shawarma! If you do, you will be asked to sign a copy of the above waiver, issued at all 20 locations. Co-founder Yasser Ali is highly offended at the idea of covering his delicious shawarma with the sweet tomato-based condiment, as others would be if you put pineapple on a pizza or ketchup on an expensive steak. People who request ketchup have been a thorn in Ali's side for a long time, enough so that he made some ads to get the point across.
America is the land of fusion cuisine, where we have taco pizza and Japanese spaghetti, but Shelby's is a Canadian chain, and pride themselves in serving tasty shawarma cooked with traditional spices and served with traditional condiments. So why does Shelby's even have ketchup in the restaurant? For the french fries, of course. -via Metafilter