What are words that can be used in puns?

Any Words can be used for puns.

Even misused punctuation can form a pun. The title of a popular book, "Eats, Shoots and Leaves" by Lynn Truss is a pun based on the use (or misuse) of a comma. Apparently a text described the diet of a koala as the book title using the comma, which should have read "eats shoots and leaves". But with the comma, the phrase infers that the koala eats, shoots something, then departs.

Basically, a pun is made when a real Word is used in a humorous way:

Ruthie rode my motorbike

Directly back of me.

I hit a bump at ninety-five

And rode on Ruthlessly. (a play on Ruth's name and the callousness of leaving her behind, possibly injured)

Most puns are based on Words that have more than one definition or Words that sound the same:

After winter, the trees are relieved. (re-leaved)

Grade school kids love the simplest puns:

How do you make antifreeze? You steal her blanket.