Obvious Jew
An OJ is a Jew so obvious, even your dog would know. They have names so Jewish, it's like they were raised in a temple. Don’t go around writing them down unless you're totally sure they're actually Jewish.
'Daniel? That’s an OJ. Even my dog knows it.'
'Rachel? She's got the name of a real OJ.'
'Ezra? That's an OJ. No need to argue.'