Some mistakes are more costly than others, as these chefs know all too well. Professionals from the back of house shared their priciest kitchen mistakes , and some of them are surprisingly costly. I can actually add my own story here — I'm glad it's finally come in handy after years of being one of my most embarrassing moments ever. I was working a shift at a fast food restaurant and customers were being so mean to me. It was the Sunday morning bingo crowd, and they were nasty and impatient to…