Dedicated to Piotrek - who really does like his chocolate cake!
Have you got a sweet tooth?
For once, it's a logical idiom. If you have a sweet tooth, you like sweet things like chocolate and cakes.
Why only one tooth? Not sure; maybe the others rotted away with all that sugar!
What is more delicious than a chocolate cake? Chocolate mudcake maybe? - here's a recipe.
Just watch out for the Australian accent, and the calories of course!