The Book Of Bunny Suicides by Andy Riley
How to explain? It's dark humor at it's best; and like The Far Side, it requires the reader to bring something to the reading: cultural or historic knowledge to decode just what the heck the bunny is doing.
It's funny, it's twisted, it's clever; as bunny after bunny thinks of some new way to exit. Like the bunny who crawls away from the oasis; or the bunny who orders the latest Harry Potter and then sits patiently under the mail drop, waiting to get conked by the heavy book. The bunny suicides are all extreme and over the top.
This is a book for adults and older teens; if you have a bunch of teens hanging out, especially those who are quoting Monty Python, bring this out. They'll love it.
The Website for the book includes some cartoons. And I should have guessed -- the author is British (and yes, without knowing that you may miss the punchline for a cartoon or two.)