Wow the pronounciation is really off here instead of 'cade' it says 'clid' which does not even exist and also 'cu' sounds more like 'nu'.
Sounds very strange in English, the usual expression being:
"You shouldn't eat with your mouth full"
Why in this sentence the English is "to speak" and in Romanian "you speak"(vorbești) and in another sentence I was marked wrong using the whole verb.... grrr
The pronunciation of "cade" is very bad
I believe that another acceptable translation would be "Nu e appropriat sa vorbesti cu gura plina!". I'm Romanian and I have not heard "cade" used in this context before.
"a se cade" is quite used in every day speech, at least in my region. Another possible translation would be "Nu este frumos să vorbești cu gura plină".