“Jiaozi” (Chinese Dumpling) is very popular in China especially in the North. Related to Jiaozi there are many Chinese expressions. For example, when parting or receiving one’s friends or relatives, you can say “Songxing de Jiaozi jiefeng de mian (literally ‘send you off with Jiaozi and welcome you back with noodles’)”. The saying means that if a person eats Jiaozi before leaving his home, he will have a smooth and safe trip; whereas if he eats noodles after he returns home, he will stay with his family forever. Another saying “Jiaozi jiu jiu yue chi yue you ” means that while you have Jiaozi with wine, your family will become prosperous. Another saying “eat more Jiaozi, you will not feel its deliciousness; drink more honey, you will not feel its sweetness” implies that if a person eats too much tasty food like Jiaozi and honey day after day, he will not feel their deliciousness. Jiaozi is made of wrappers and fillings, and it is usually boiled in water before being served. Many Chinese sayings are related to these characteristics of Jiaozi. Here I will introduce some of them to you.
茶壶煮饺子 ——（肚里）有货倒（道）不出来 To boil Jiaozi in a teapot —They could not be poured out.
中国人喜欢喝茶，每家都有一两把茶壶。茶壶有各种形状，不过都是肚子很大、壶嘴很小。饺子要用大一点儿的锅来煮，如果用茶壶来煮饺子，由于茶壶的嘴儿小，饺子很难倒出来。 “有货倒不出来”的“货”由“饺子”泛指“东西”，“有东西倒不出来”在这里还有“想说的话说不出来”的意思。有意思的是这里的“倒”和“道”谐音，而“ 道”在汉语里也有说话的意思。“茶壶煮饺子——（肚里）有货倒（道）不出来”就是说，一个人头脑里装了很多知识和学问，可是由于口才不好，所以很难把想法表达出来，或者表达不清楚。例句： A：听说李老师学问挺大的，可是讲起课来好像没什么意思。 B：可能是“茶壶煮饺子”吧。 Since the Chinese people enjoy drinking tea, almost every household possesses a teapot. Teapots have a big belly and a small spout. When Jiaozi is boiled in water, it is better to use a big pot. If you boil ji aozi in a teapot, it is difficult for you to pour out when it is ready because of the small spout of the teapot. In the second part of the saying, “you huo dao bu chu lai” literally means that “goods could not be poured out”. “Goods” here means Jiaozi, which can generally refer to “something”. “Something could not be poured out” has another layer of meaning “one has the difficulty in expressing himself”. Interestingly, the two Chinese characters “倒” and “道”are homophony, the former literally meaning “pour”, and the latter “speak”. Therefore, the Chinese saying “To boil Jiaozi in a teapot—They could not be poured out” also means that even if a person has acquired erudite knowledge, he might not express himself clearly or find it difficult to express his ideas. Example: A: It is said Mr. Li is erudite. But his lecture seems very dull. B: Don’t you know the saying “To boil Jiaozi in a teapot—They could not be poured out?”
source: http://www.hellomandarin.com