The first time I signed out one of Daniel Pinkwater's books from the library, I did it more to amuse my husband than anything else. Adam has fond memories of reading The Snarkout Boys books during his young adulthood, and I've given Adam various Pinkwater books as gifts over the years.
The first Pinkwater picture book that I signed out was Bad Bears and A Bunny: An Irving and Muktuk Story. I was curious about what made the bears "bad." At the time, I didn't realize that this was one of several books about Irving and Muktuk. I definitely recommend starting with Irving and Muktuk: Two Bad Bears. I think that the stories make more sense (as much as anything in them makes sense) with that book.
Most of the Irving and Muktuk books involve plots to steal large quantities of blueberry muffins, and there's usually a major conflict between the polar bears and a bunny. The books are set in Bayonne, New Jersey, the blueberry muffin capital of the world.
Dang. Now I'm craving blueberry muffins.
Although Irving and Muktuk don't do anything much worse than stealing muffins, readers who want a more universally-likeable polar bear character might prefer the books about Larry the Polar bear. Larry lives in a hotel that was named after him (long story) and works there as a lifeguard. From the point that Larry's mom kicks him in the head and tells him to get lost to his first sleepover party, there's a lot to enjoy. I would be remiss if I didn't comment on Jill Pinkwater's wonderful polar bear illustrations--these really do help make the zany storylines work.
So, if you're in the mood for a weirder-than-average children's book and have a fondness for polar bears and/or muffins, check out the Larry books or the Irving and Muktuk books.