Okay, I read a really good book a while ago, but I can't remember what it was named and it's really bugging me!

It was pretty much based on puns and idioms and sayings and stuff. The main character was a little boy and I believe he got to this weird world through a phone booth, but that might be wrong. He has a dog with him and I think the dog had a clock around his neck or something. And for some reason this little kid was allowed to drive in this world. Also, there was a point in the book when the boy made an assumption and "jumped to conclusions" and ended up literally jumping to an island called Conclusions.

I'm pretty sure the cover of the copy that I was reading was blue and had the boy in the telephone booth with the dog nearby.