Syllepsis is a form of pun in which a word within a sentence can be interpreted in two entirely different ways without changing anything about the sentence.

(Where this is unintentional, it is called ambiguity)

In this example from Shakespeare, the word "lie" could mean either 'to go to prison' or to 'tell a lie'

"...your imprisonment shall not be long. I will deliver or else lie for you."

--Richard III, Act I, Scene i, Line 115

See also: