This sound is best known as an online meme quote rather than a clearly documented clip from a single mainstream source. The phrase spread through reposts, short-form edits and meme communities that use “plap plap plap” as exaggerated slang for a blatantly sexual joke. It shows up often in anime-adjacent posts, reaction videos and absurd caption memes, where the repeated wording makes the bit instantly recognizable. Its staying power comes from that rhythm: people hear the first words and already know the joke is about to go off the rails.