I’ve given myself a paper cut on the nasal septum, which separates the nostrils. It was very painful.
A previous thread where this very question was discussed, including a scientific explanation for the phenomenon.
I cut my finger joint nearly through to the nerves and tendons and didn’t feel a thing either. So whats the reverse, why does a sharp knife cause so little pain? It certainly didn’t hurt me and it nearly did immeasurable damage to my finger.
You probably damaged the nerve. If the nerve is unable to transmit the pain message, you, of course, won’t feel the pain. But I feel your pain. 
jjimm,
I may be a sick puppy, but adding lemon juice hurts a lot at first, and then it doesn’t hurt anymore after that. It’s a trippy sensation as well. You know it’s going to sting, you put the juice on anyway, there is a brief moment when nothing happens and then WHAM! you get an intense feeling (like when the Doctor says you might feel a slight pinch), and then nothing.
I’ve also noticed that when I have a paper cut on the top of my finger and I reach into my front pocket, I re-rip open the cut. That is why I started using crazy glue to keep it closed and protected from re-ripping. The crazy glue also keeps water out of the cut, including hot soapy dishwashing water.
By the time the crazy glue falls off the cut is healed enough not to keep re-opening.
Of course, if you don’t want to do the dishes, telling your SO that you have a paper cut is a good excuse, unless you have gloves laying around…
This one time, in paper cut camp, I got a paper cut on the cuticle of my left index finger…
There’s a liquid you can apply called “Second Skin.” I used to use this when I used to bowl and developed a blister on my thumb. I still use it with an occasional raw blister or abrasion on my hand before I play tennis. It really works wonders. It really is like a new skin.
Lip…I don’t lick envelopes any more.
I would like to note that this was Pops’ first or second post to this board, and it made me laugh out loud. Welcome to the SDMB!