Cats & Toothbrushes

What is it with cats and toothbrushes? Why are they hypnotically, inexorably, irresistibly drawn to them? It's not just mine, Youtube shows many many people have seen the same phenomenon. The soft grippy-handled Oral-B I used to have seems to work the best. When done with an old used tooth brush, if you've already got one or two in the tool box (for cleaning off battery terminals) then use it on your cat - or donate it to someone locally with feline allergies who wants to pet a cat but doesn't want to get cat dander and drool on their hands.