a treif-jew

this is an amalgamation of the terms a treife and a jew. It's a term of derision or insult, usually used by jews against other jews, to define 1) a jew who behaves and acts like a goy or 2) a jew who has converted out of judaism into another monotheistic religion.

two jews meet on the street and one of them is eating a Black Forest ham and cheese sandwich.

jew a) how dare you eat this junk, you a treif-jew, you are disgrace to judaism.
jew b) thanks for reminding me, but please just stuff it and be on your way.