Commenting, liking and reacting on the Internet have become ubiquitous. In almost every online interaction, people have the opportunity to show their approval of comments. It has also become common to express several other feelings such as anger, love, and compassion through emojis. Previous research suggests that "online spaces represent a cultural turn towards new democratic discourse" (Suhr 2014, p.77) requiring readers to be critical thinkers so that they do not fall prey to readily available information. Critical thinking is an indispensable skill to teach to our students today who are also frequent users of online spaces. Unfortunately, there is little research on how "liking" a comment can be used to promote critical thinking and deep learning. This article discusses the use of a simple guided critique of online comments to encourage students to think critically about what they are reading or viewing. Data included students' written analyses of comments posted in response to a TED talk, students' pretest and posttest critical thinking performance scores, and students' answers about the effectiveness of the analysis activity. Findings demonstrated that students applied four criteria to judge the plausibility of online comments (informativeness, consistency with prior belief and current context, objectivity, and format/appropriateness). Pretest and posttest comparison showed that evaluating online comments provided students with several alternatives to consider which had a positive impact on their critical thinking skills. Using comment sections is a promising instructional tool to improve critical thinking skills.