In Judaism, a circumcision is a sacred covenant between God and the Jews. But in America today, we have lost our exclusive rights to it. No longer can you tell if someone is Jewish or not by taking a look at their schlong; one will find that many, if not most, goyishe parents will circumcise their children.
Of course, this is usually done at birth for health reasons, not as a senior citizen on a whim, which is apparently what happened with Marlon Brando. The stories on when and why he did it diverge: some say he did it in his 60s, some in his 70s; some say he did it himself (1, 2, 3, cringe!), and some say that he did it as part of his conversion to Judaism. And thus, in a roundabout way, his appearance on our website.
It's just a rumor, as far as we can tell. There is no real evidence, circumcision or not, that Brando became a Jew late in his life. There's just a lot of conflicting stories. He sent his children to Jewish schools. He made anti-semitic comments on Larry King. He made statements lauding Jews. He made statements burying them. He likes a good bagel with lox and cream cheese. He put mayo on his brisket. Who knows?
Here's what we know for sure: circumcising oneself may at one time have been a sign of Judaism. But now? More like sadism with a touch of insanity. Even if you are Marlon Brando.