方便 (Fāngbiàn) Convenience

A: Nĭmen zhōngguó de fúwùyè zhēn shì zhōu dào.
A: 你们      中国        的 服务业   真   是    周    到。
The service industry in China is really thorough.
B: Nĭ cóng nă kàn chū lái de?
B: 你   从   哪  看   出  来 的？
wher did you come up with that?

A:  Nĭmen de fúwù hángyè cháng cháng tiē zhe “wèi gù kè tí gōng fāng biàn,” zhè yàng jiù ké yĭ
A: 你们      的 服务  行业      常      常      贴  着   “为 顾 客 提   供    方    便”， 这    样   就 可 以
hĕn fāng biàn zhăo dào wèi shēng jiān.
很     方    便    找    到   卫    生     间。
The service industry here in China has put signs up everywher with the sentence: “providing customers with convenience,”which helps us find the toilet so easily.

Analysis
In China, the phrase 方便(fāngbiàn) has two meanings. One means “convenient” and the other means “going to the washroom.” But, in China’s service industry, it only means convenient. So in this joke, ‘A’ only knows the second meaning, thereby misinterpreting the meaning of the sentence.