The 'I Didn't Know You Were Chill Like That' meme stems from a viral video featuring a person making a shaka (🤙) hand gesture while someone off-camera expresses surprise at their laid-back attitude. The phrase became a popular TikTok sound and social media reaction, used to describe moments where a person, animal, or even an inanimate object unexpectedly displays a 'chill' or cool demeanor. It often parodies social interactions where someone's reputation is suddenly redeemed by a simple, vibe-checking gesture. The meme has since evolved into various image macros and video edits, solidifying its place as the ultimate internet shorthand for approving of someone's energy and unexpected coolness.