RTSM is an abbreviation that stands for 'Read the Stupid Manual.' It is often used in a humorous or sarcastic way to suggest that someone should read the manual or instructions before asking for help or asking a question that is already answered in the manual.
RTSM is not as widely recognized or used as some other texting abbreviations. It is more commonly used in niche communities or by individuals who are familiar with technical manuals or instructions.