This study explores the dynamics of online discourse in controversial discussions. By analyzing threads on topics such as antinatalism (the belief that it is morally wrong to reproduce), climate change optimism, and overpopulation, the study identifies how participants manage disagreement, negotiate meaning, and shape the tone and development of the debate. Drawing on theories such as Brown and Levinson's Politeness Theory, the findings reveal the importance of emotional appeals, humor, irony, and framing in fostering or hindering constructive dialogue. The results emphasize the double role of tone in online forums. Polite and measured responses tend to de-escalate conflicts and promote meaningful exchanges, while emotionally charged or confrontational language often intensifies divisions. Similarly, the use of inclusive framing and pragmatic markers facilitates collaborative discussions, whereas extreme rhetoric and exaggeration contribute to polarization. The study highlights how humor and irony serve as tools for softening face-threatening acts and easing tension in heated debates. Online forums are spaces where discussions easily take unexpected turns, influenced by both individual linguistic choices and the broader dynamics of digital communication. By providing insights into the rhetorical and pragmatic strategies used in online discussions, this study contributes to a deeper understanding of how communication unfolds in digital spaces. The findings offer practical implications for educators and communication trainers aiming to promote respectful and productive online interactions, especially on divisive topics that demand nuanced and collaborative engagement.