This phrasology is used to describe a situation in which a person is either eating a Maneschwitz cracker or is in a situation where they have forgotten something.
Erin showed up to class one day, but exclaimed "Jewish crackers!" when told to hand in an assignment that she has forgotten.
The Jewish perfume is when you are sitting in a chair getting a blow job and you fart. A cloud of noxiousgas is expelled from your anus and floats around the head of the person fellating you.
Man, Last night I gave this slut I met at the bar a Jewish perfume... Luckily she didn't pass out till AFTER I finished.
When some one is acting ungreatful, or like a brat. Can be used in a joking matter.
Person 1: dude Alex was acting like such a Jewish mermaid last night.
Person 2: yea, I know. I can't believe he flipped out on his mom over a sand which!