The exact original source of this clip is not clearly documented from the available information, but it is used online as a short Dutch meme phrase and joke reaction. Sounds like this often spread through chat apps, reposted edits and small soundboards because they are fast, quotable and easy to drop into videos. “Je moeder is een plopkoek” stands out because it mixes a familiar “your mother” setup with a weird, harmless word, giving it a silly tone that keeps it shareable.