"Oh there's such a better word for [insert every day concept] in [insert target language] but it's just too difficult to explain to you if you don't know the language"
"The conjunctive can go suck a big fat one"
[Eternal debate on what "fluency" really means, or if it exists at all]
"If you know one [insert major language family] language, then you really know them all" (I'm guilty of this)
"One day I really want to learn [insert obscure language with less than 500k speakers], it just seems so cool"