Given the increasing realism of social interactions online, social media offers an unprecedented avenue to evaluate real-life moral scenarios. We examine posts from Reddit, where authors and commenters share their moral judgments on who is blameworthy. We employ computational techniques to investigate factors influencing moral judgments, including (1) events activating social commonsense and (2) linguistic signals. To this end, we focus on excerpt-which we term moral sparks-from original posts that commenters include to indicate what motivates their moral judgments. By examining over 24,672 posts and 175,988 comments, we find that event-related negative personal traits (e.g., immature and rude) attract attention and stimulate blame, implying a dependent relationship between moral sparks and blameworthiness. Moreover, language that impacts commenters' cognitive processes to depict events and characters enhances the probability of an excerpt become a moral spark, while factual and concrete descriptions tend to inhibit this effect.