How to Send Back Food at a Restaurant Without Pissing Off Your Waiter

While the majority of the restaurant waitstaff you encounter will probably not spit or pee in your food if you send it back, it's a common joke or paranoid concern that enters the conversation the moment someone decides to send their plate back to the kitchen.

Source:
http://lifehacker.com/5887579/how-to-send-back-food-at-a-restaurant-without-pissing-off-your-waiter