Who knows the story of making jokes because of typos or homophones?

There is a foreign teacher teaching students to spell words in English class. The teacher asked,' How do you spell a pig?' How do you spell "pig"? Then a classmate stood up and answered: Teacher P-U-G U-G said: You spelled it wrong, {classmate, you spelled it wrong}, that is, spelling it for pig is' I' (I), not' U' (you). Pig is me, not you. That classmate retorted: the pig is' u' (you), not' I' {the pig is' u' (you, not me}. The whole class laughed! Foreigners don't know what it means yet! He suddenly realized and smiled.

Homophonic, a joke you played.