早点 Záodiăn Breakfast

卡尔:你们中国人的确是一个勤奋的民族。
         Nĭmen zhōngguó rén díquè shì yí gè qínfèn de
         mínzú.
         Your Chinese are really a diligent nation.
张力:你怎么看出来的？
         Nĭ zĕnme kàn chūlái de?
         How do you know that?
卡尔:我在街上走的时候，常常可以看到路旁的招牌写着
        “早点”两个大字，提醒上班的人不要迟到。
         Wŏ zài jiēshàng zŏu de shíhou, chángcháng kéyĭ
         kàndào lùpáng de zhāopai xiĕ zhe "záo diăn"liǎnggè
         dà zì, tíxĭng shàngbān de rén búyào chídào.
         I can always see the two words "早点" on the
         signboard when walking on the street, which
         reminds people of not being late.

Analysis
早点(zăodiăn) in Chinese has two meanings. One refers to breakfast and the other means coming early. But 早点(zăodiăn) in the joke means breakfast.