For some reason, it's completely endearing and hilarious for bunnies to try to commit suicide. Perhaps it's because the ingenious and absurd machines, traps, and situations they put themselves in require a tremendously dark wit, and we don't expect these dandelion munchers to express such cynicism.
There are a number of people who try to imitate Andy Riley's bunny suicide comics, and they sometimes come out all wrong. For example, they tend to show the death of the bunny. This is unfortunate, because the joke is in the reader's mind, trying to figure what the bunny is thinking and how the suicide will work, not showing the reader the gruesome death.
People with a dark sense of humor (and, of course, their snail mail friends) will enjoy this book of post cards, and judging from the way it has been out of stock at some bookstores, there are a lot of us out there.