I was talking to someone about puns and she said that it's a play on words, e.g. "those two pears are a pear of green balls" (sorry about the awful example, I couldn't think of any others on the spot).
I argued that this is a pun:
John Lydon looked out of his bedroom window and said, "Ah, how I love country life". (John Lydon stars in a butter advert which has the phrase "country life" in it).
Which is a pun?