A pun refers to the usually humorous use of a word in a way that suggests two or more of its meanings or the meaning of another word similar in sound. For some, a pun is the lowest form of humor, but for others, it is an art form and as a rhetorical device it can be very effective in making a serious or humorous point.

Pun
noun
a joke exploiting the different possible meanings of a word or the fact that there are words that sound alike but have different meanings.
“The moment I accept that there’s an artistic, redeeming quality in puns, I have a horrible feeling I’ll get hooked.”  John Oliver Comedy Central
The usually humorous use of a word in such a way as to suggest two or more of its meanings or the meaning of another word similar in sound. For some, a pun is the lowest form of humor, but for others, it is an art form and as a rhetorical device it can be very effective in making a serious or humorous point.

 pun  examples

“Over the years, I have been subjected to many indignities, all for the sake of Art. If I ever catch him, I’m going to kill the guy.” Bob Hope The Road to Hollywood: My 40-Year Love Affair with the Movies
“I have mood poisoning. Must be something I hate.”  Marilyn Manson

As a literary device that plays on words, puns can be very funny, clever and effective.  Bad puns are often considered to be cheesy. Puns are used a lot in humor. Puns make you think and their ambiguity requires you to interpret the statement in more than one way.  Comedians love wordplay, especially the pun.