This line is spoken by Scout, one of the playable classes in Valve's Team Fortress 2. The quote became widely shared in TF2 fandom clips, class compilations and meme edits because it sums up Scout's loud, fearless personality in one short speech. Over time, the opening phrase "grass grows, birds fly, sun shines" became recognizable on its own, even before the punchline lands. It still shows up in gaming memes and character edits whenever creators want a cocky, instantly recognizable intro.