When you dislike someone so much that anything they do, no matter how minor or inoffensive, annoys you beyond any rational level - exemplified by the sentence "look at that bitch eating crackers like she owns the place".
A woman who meets an attractiveness threshold above which you would easily forgive minor transgressions such as eating crackers and leaving the inevitable crumbs in your bed.
The British version "I wouldn't kick her out of bed for farting", while similar in spirit, lacks some of the subtlety of this version.
When you just feel bad in general and cannot pinpoint the source. You have no symptoms of sickness such as a runny nose or nausea, but you really feel terrible.