"Oh, fudge!" (4)
(Other definitions for rat that I've seen before include "Domestic rodent" , "one escaping doomed vessel?" , "that gets out of stricken vessel" , "Cad" , "person doing shopping" .)
(Other definitions for rats that I've seen before include "Tells" , "Curse" , "Annoyed expression" , "Blast" , "Oh no" .)