I don't remember when I read a Dr Xargle book for the first time, but I do remember that it was Dr Xargle's Book of Earth Relations and that I laughed until I cried, and that it was before I had children. It was the game of "Be Quiet the Grown-ups Are Talking" and the expressions on the faces of the kids that reduced me to tears of mirth. Even now that I have read it LOTS of times, I still often have to stop to catch my breath from the giggles I get when I read it.
There are several Dr Xargle books; the only one we don't have is the book of Earth Weather. In fact, I didn't even know this one existed until about three minutes ago when I checked the surname of the author on Amazon. I can now feel my index finger of my right hand hovering over that 1-click button. All of them are brilliant. Earth Relations is my favourite - this deals with the complex relationships between Earthlings. The Earthlet one is a great present for a new parent or sibling. The Tiggers and Hounds ones are great for pet owners. There's a Xargle for everyone.
The premise is that Dr Xargle is an eminent alien school-teacher who lectures his students in the ways of the Earthling. There are some wonderful turns of phrases. For example the earthlet is unable to keep itself warm, so it must be wrapped in "the hairdo of a sheep".
The pictures are fantasic, and the kids loved flicking through the books long before they could read; always the sign of a great picture book. However, it's the text that makes it for me. The kids enjoy them as much as I do, but it's a close run thing. Children know when the book you are reading to them is fun for you too, and that enhances their enjoyment. That's my excuse for never reading books I hate to kids anyway - life is just too darn short.