Sometimes spelled 'treyf'. It's a transliteration from Yiddish.
Metaphorical: Mike's urine test was treif. He use'd Bill's piss because he was tokin' last Tuesday and didn't want it to show up.
noun, uncountable and countable
1) an unreasonable Jewish contempt for food, culture, nationality, religion, race etc
2) someone who always complains about anything in sight