You're an apple

There are many varieties of jokes and some are characteristic for English. For example puns are widespread in English as opposed to Czech. If you want to include jokes, or humour generally, into your lesson, a good source of puns could be the "Annoying Orange." You can follow his channel on youtube (http://www.youtube.com/user/realannoyingorange?blend=3&ob=4), or even better, you can join his profile on Facebook and get your weekly dose of his new adventures there. Oh and btw, Why did the elephants get kicked out of the pool? Because they kept dropping their trunks! HAHAHA! You're an apple.