It's difficult to avoid a sneaky feeling that business is much too serious to be taken lightly. In fact, it's much too serious NOT to be taken lightly. These books take a humorous view of business, but there are some real lessons there too.
 

Scott Adams

Dilbert and the Way of the Weasel
Where previous Adams management books (as opposed to pure cartoon collections) have achieved some balance between the positive and the negative, this plunges whole heartedly into the BAD side of business. This is all about being a weasel - a weasel manager or a weasel employee, out to screw everyone and the business for as much as you can get - is not just about being negative, though. The fact is there's plenty to learn, because pretty well everything in here is what not to do, and there are very few of us who work in organizations where some of these bad practices don't occur. New 11 November 2003

The Dilbert Principle.
With a combination of witty text and devastatingly funny cartoons, Scott Adams illustrates everything you can do wrong in business. Superb.

The Dilbert Future: thriving on stupidity in the 21st Century.

Adams has done it again, managing to mock both management text books and everything business can throw at us in the future. Slightly more words and less cartoons, but still hits the spot.

The Dilbert Future

The Joy of Work: Dilbert's Guide to Finding Happiness.
This third venture into business writing is driven by the e-mails Adams receives from his fans, and as such contains less words of business wisdom than previous attempts. Even so, the familiar mix of cartoons and commentary still makes it a worthy addition to the collection. New 9 December 98

John Gall

Systemantics - how systems work and especially how they fail.
Like Parkinson's Law, the humour in this slim systems book can occasionally be wearing, but it's right on the mark in describing just how systems get to be too big, don't do what they are supposed to and generally take charge.

C. Northcote Parkinson

Parkinson's Law.
Parkinson's Law (work expands to fill the time available for its completion) is quoted so often, that it has assumed a mythical quality like Murphy's Law. In fact it is the underlying theme of this early (1958) humorous business book. Sometimes the humour is a little heavy-handed, but there's a lot more on how not to run a business in there. Worth buying for the nuclear reactors / bicycle sheds discussion alone.