One reason is that sometimes jokes contain playful use of words, words have more than one meaning or they are not intended to be used to convey "literal meaning" . Said another way, words in jokes may contain rhymes, multiple meaning words or convey "figurative meaning". So, the next time someone turns to you and says: "What do you call a bee that drops things?", think of why the punchline: "A fumble bee!" makes the joke funny! For more information on understanding and using humor, please check out my monthly speech/language challenge page.