The 'That Guy' meme serves as a versatile cultural shorthand for identifying individuals who embody specific, often annoying, stereotypes or social faux pas. While it doesn't originate from a single source, it evolved from early 2010s image macro culture where stock photos of smug or overly enthusiastic men were used to represent the ubiquitous 'guy who...' trope. It is commonly used to call out relatable social errors, such as being too loud in a quiet space or over-explaining a simple concept. The template resonates because everyone has encountered 'that guy' in real life, making it a staple for relatability-based humor across Reddit, Twitter, and office Slack channels.