比茶壶还热 -- hotter than a teapot!

昨天晚上上中文课，一段话里，妈妈说：比茶壶还热！所以我们的老师教我们：茶壶里煮饺子倒不出。意思是：知道很多东西但是不会表达的人。 昨天晚上学生只是我和马克。一老师说了这个，我们就说：数学家！

In one of the dialogues we studied in class last night, the mother used the expression 比茶壶还热 (bǐ chá hú hái rè) -- hotter than a teapot! So our teacher taught us another phrase:

茶壶里煮饺子倒不出
chá hú lǐ zhǔ jiǎo zi dào bù chū

Literal translation of words:
茶壶 -- teapot
里 -- inside
煮 -- cook, boil
饺子 -- dumplings
倒 -- pour
不 -- not
出 -- go out

So the phrase literally means "dumplings cooking in the teapot, they don't pour out". The phrase is used to describe someone who has a lot of knowledge inside, but can't express it well. Last night a lot of people weren't there; it was just me and 马克 (mǎ kè) -- Mark, a computer science professor. When we heard this, we immediately exclaimed, "数学家！" (shù xué jiā!) -- "Mathematicians!"