This is a bilingual English/Spanish joke-- especially good for a class of native Spanish speakers. It also illustrates an important gramatical difference between languages (genders of nouns).
An Englishman went to Spain on a fishing trip. He hired a Spanish guide to help him find the best fishing spots. Since the Englishman was learning Spanish, he asked the guide to speak to him in Spanish and to correct any mistakes of usage. They were hiking on a mountain trail when a very large, purple and blue fly crossed their path. The Englishmen pointed at the insect with his fishing rod, and said, "Mira el mosca!" The guide, sensing a teaching opportunity, replied, "No, senor, 'la mosca'... es feminina."
The Englishman looked at him, then back at the fly, and then said, "Good heavens... you must have incredibly good eyesight."
This is a riddle. It works well if you let the students ask yes and no questions about the situation, before revealing the answer.
Q: A man goes into a bar and asks for a glass of water. The barman pulls out a gun, and points it at the customer. "Thank you" replies the customer and walks out. What happened?
A: The customer had hiccups.
I've used this in many countries in Eastern Europe. It always works - a shock as a hiccup cure appears to be an international thing.
The Perfect Son.
A: I have the perfect son.
B: Does he smoke?
A: No, he doesn't.
B: Does he drink whiskey?
A: No, he doesn't.
B: Does he ever come home late?
A: No, he doesn't.
B: I guess you really do have the perfect son. How old is he?
A: He will be six months old next Wednesday.
A family of mice were surprised by a big cat. Father Mouse jumped and and said, "Bow-wow!" The cat ran away. "What was that, Father?" asked Baby Mouse. "Well, son, that's why it's important to learn a second language."
The doctor to the patient: 'You are very sick'
The patient to the doctor: 'Can I get a second opinion?'
The doctor again: 'Yes, you are very ugly too...'
I use this joke for retelling in reported speech.
Son- Dad Why doesn't the law permit us to have more than one wife?
Dad- When you get married, you will realize that the law is in our side. My dear son!