Anecdotal evidence and scholarly research have shown that a significant portion of Internet users experience regrets over their online disclosures. To help individuals avoid regrettable online disclosures, we employed lessons from behavioral decision research and research on soft paternalism to design mechanisms that "nudge" users to consider the content and context of their online disclosures before posting them. We developed three such privacy nudges on Facebook. The first nudge provides visual cues about the audience for a post. The second nudge introduces time delays before a post is published. The third nudge gives users feedback about their posts. We tested the nudges in a three-week exploratory field trial with 21 Facebook users, and conducted 13 follow-up interviews. Our system logs, results from exit surveys, and interviews suggest that privacy nudges could be a promising way to prevent unintended disclosure. We discuss limitations of the current nudge designs and future directions for improvement.