This groan comes from Plants vs. Zombies, the tower defense game released by PopCap in 2009. The game’s zombie noises became memorable because players heard them constantly during matches, and many individual effects were later clipped and shared online. The groan still shows up in meme edits, gaming compilations and nostalgic videos because it is instantly tied to the series and easy to recognize even in a very short clip. It is often used like a lightweight reaction sound rather than a scary horror cue.