* "I'm reading a book about anti-gravity. It's impossible to put down!" (This pun plays on the double meaning of "put down," which can mean to stop reading or to place something on a surface.)
* "I used to be addicted to soap, but I'm clean now." (This pun uses the word "clean" in two ways: to be free from dirt and to be free from addiction.)
* "I wondered why the frisbee was getting bigger. Then it hit me." (This pun uses the word "hit" to refer to both the frisbee landing and understanding a joke.)
Here's a tip: Puns are often used for humorous effect, so try to use them in a lighthearted and playful context.