I have this thing where if I leave my thumb fingernails hanging on by just a bit when I trim them, then run my thumbs against clothing (or anything frictiony) so that the finger nails drags along, I get a shooting "tickling" sensation in my thumbs and running down from my neck down to my upper chest. It gets so intense that I cringe up after 4-5 seconds. In fact I look forward to days when I trim my nails so I can do this. After a couple min my thumbs get numb, but like a really pleasurable numb (I know, sounds weird), and after 10-15 min I almost get dizzy from it.

I have yet to meet someone who has any idea what I'm talking about. Is this some kind of cross wiring in the brain? And the fingernail has to be hanging on in a certain way, otherwise it's much less apparent