This sound comes from Team Fortress 2, Valve's class-based multiplayer shooter first released in 2007. The speaker is the Sniper, one of the game's most recognizable mercenaries, known for his Australian accent and dry one-liners. Short voice clips like this spread through TF2 videos, memes and soundboards because they are instantly recognizable to players and easy to use in quick edits. Its popularity lasts because the line is simple, flexible and tied to a long-running game with a strong online culture.
About this sound
A short "G'day" voice line from the Sniper in Team Fortress 2, used in memes, intros and quick reaction edits with an Australian vibe.
This clip is the Sniper from Team Fortress 2 delivering a brisk, friendly "G'day" in his dry Australian accent. It is very short and clean, which makes it easy to drop into a cut for a fast greeting, a smug entrance or a joke reveal. The line lands with a calm, confident tone rather than a loud punchline, so it works best when you want a small character beat that fans instantly recognize. Even people who do not know TF2 usually read it as a casual hello with a bit of attitude.