I don't know why, but I've suddenly been overwhelmed by nostalgia and really need to find this story, I remember listening to it on a CD but it was probably a book originally. The story is for kids just to clarify. I THINK that the book title is just the name of the Alien in said story. The main protagonist is a young boy who befriends an alien stranded on earth (I think the alien is also young), the boy I beleive lets the Alien hide in his house, the Alien is also for some reason is fixated with ketchup, which he refers to as "Sauce of the tomato, fifty seven". The alien and the boy manage to contact the aliens parents using a lorry radio or something with the help of a man. Thats pretty much all I can remember. If anyone has any idea what this book may be please tell me!
A quick Google search for "Sauce of the tomato, fifty seven" yields "The Invisible Boy" by Sally Gardner. From Publishers Weekly:
[T]he lad takes solace in the company of Splodge, an alien whose spaceship crashes in the garden ("I come in peas. Take me to your chef," says the visitor, explaining his search for "sauce of the tomato fifty-seven"—aka ketchup).