It's a joke that can't even be explained anymore. The original thing it was working from was actually quite sad. A little girl (I think?
Might have been a boy) said her mom was a lesbian in school and her teacher made her promise not to say it anymore. The ACLU filed suit. "Cep my mouf shut" is from the original.
...commenter rhymes with mofo provides the original. The student was (apparently) a boy, Marcus.
![](https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgVs5OpMqyom3xb9Qp60bEbVdl_sRNlx4fkEHb592gLVPF5uuRAMhomE-jU07d8txy4g8xdPZb9LJXdoqKKk75v4h8OWNjyEnfBj8JXArLWAIIwYl5hyejwGK2pBlst0-QA3sWa/s1600/lesbian.jpg)