I love Five Guys...there is one down the street from our place in Miami.  Last time we were there my wife claimed she had a bad burger and was quite ill a little while after eating there.  Later that night she mentioned that she had eaten a cookie on a plate in the kitchen....I had found the cookies in the back of a cupboard and they were white with mold, having been there since the previous owners moved out.  She thought it was frosting.  LOL  Poor Five Guys were blamed by exonerated.