Rosie O'Donnell -- I'm A Lesbian Cougar Now!

Rosie O'Donnell says temptation is everywhere now that she's single ... especially when she's face to face with some obsequious students from Barnard College.

The freshly single O'Donnell showed up over the weekend at "The Vagina Monologues" in NYC.

Rosie announced she and wife Michelle Rounds were going their separate ways, the day before she released her HBO documentary talking about life as a married woman.