My oldest son has an undying love for the
Super Fly Guy series by Tedd Arnold. These books are really funny and really easy to read. They are a little "gross" but not over the top. They are perfect for me to stack up in his bed for him to read to himself at night.
These books also pass my test for no "I hate grownups" themes and also no "My Siblings are My Enemies" themes. I HATE books that try to drum up that crap.