Round smooth objects with no sharp edges corners or seams.
Hairbrush handles
Cooking utensil handles
Long plastic bottles hair/body spray. (Watch for sharp plastic seams.)
Curling iron. Off obviously
Sharpie markers
Chapstick
Deodorant
Bubble wand
Veggies
Fingers
Slender drink bottles. Plastic.
Be sure nothing too short to get stuck once inside you.
Sharp test is run tongue over it if you feel scratch or cut it’s not good for the other holes.