Yes,toothpaste as a thermal paste is a joke.
However, little known fact: toothpaste can work wonders at repairing scratched CDs - I've done it myself. Take a little toothpaste, spread it over the scratches on the disk, and clean genlty with an soft cloth. A chemist friend told me it was probably because the hydrated silica crystalizes in the scratch and then refracts light from the CD laser... or something science-y like that.