Chinese proverb: Man run behind bus...
Chinese proverb: Man run behind bus get exhausted, man run in front of bus gets tired.
This joke is probably racist. The racism in this joke is the implication that Chinese people cannot speak English well. The only reason why it is included here is that it is also a double pun (or, as Bryan King would call it, a double double entendre).
In this joke the word "exhausted" (which usually means very tired) also could reasonably mean surrounded by exhaust fumes. The word "tired" in this joke also has the additional meaning of "run over with a tire"