His friend Doug stops him and asks, "Hey Bob! Whacha get the case of beer for?"
"I got it for my wife, eh." answers Bob.
"Oh!" exclaims Doug, "Good trade."
"No no no no! you misunderstood me. I'm bringing this beer to my wife!" explains Bob.
Anti-humor is a type of indirect humor that involves the joke-teller delivering something which is deliberately not funny, or lacking in intrinsic meaning. The practice relies on the expectation on the part of the audience of something humorous, and when this does not happen, the irony itself is of comedic value.