As a few others have said...
Rubbing your eyes really hard when they're itchy.
Writing on a banana with a biro.
Popping bubble wrap.
Though I HATE anything being in my ears! And hate the feeling of eardrops.
ALSO I do enjoy:
Having a tiny bit of very slightly split fingernail, and dragging it along a bit of fabric, so it makes a clicking sound as it catches. (Hard to explain sorry!)
Rubbing the top of my cat's head with my chin.
Popping zits! (Haven't had any for some years though!)
Cutting my toenails.
I have my ears pierced 5 times in each ear, and every 2-3 months I love taking out all the studs, and cleaning off all the crap/dead skin cells/dead soap off them with my fingernail.
Wrapping my hair bobble around my forefinger, 3 or 4 times til it's tight. I enjoy the feeling of the pressure on my finger. Also like a few others, I enjoy someone lying on my whole body. Again, I enjoy the feeling of the pressure.
Pushing my hands right down into a pot of maggots!
I wanna say having a good satisfying poo, but I won't as it's TMI. 😆