This is taken from the Simpsons. A guy whose name is Moe, who is a bartender, is shocked to see so many people in his dive. So, he makes a comment which is not admied by the visitors that heard it.
- Whoa! Look at all the meat in the seats!
- That grosses me out. Good-bye.
- Would you look at me? My mouth is running like a toilet!
Moe says that his mouth is running like a toilet! This is another expression I've never heard of. Have you ever heard it? What are the other (more common) ways of expressing this?
It seems to me that he himself is disappointed at the way he speaks. So, in Russian it could be translated as
У меня не язык, а ершик для унитаза. - I don't have a tongue, but a toilet brush.
Вы только гляньте на меня у меня не рот, а помойка. - Have a look at me I don't have a mouth, but a swill (dishwater).
Ну что за ужас, у меня вечный словесный понос. - What a horrible thing! I've got an eternal verbal diarrhea.