[[WMG: Howie Mandel has cartoon world powers.]]
He discovered these by learning how to use the voice of Bobby, which summoned Bobby from the cartoon world which Howie is originally from. Howie can switch between Cartoon Dad and himself at any time even in the real world (see "The Visit to Aunt Ruth"), and uses this to become Bobby's dad in the cartoon world.
* Seems to be true.
[[WMG: Derek is so mean to Bobby because he's jealous of him.]]
Since Bobby is little, he doesn't seem to have many responsibilities, while his older brother and sister Derek and Kelly do. That, and once Bobby was born, he 'stole' Derek's spot as the baby of the family, which would probably result in sibling jealousy, especially since Derek might've been so used to getting what he wanted by then.