system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why will spicy food burn my mouth, lips, eyes, or genitals (if touched) but not my hands or other body parts?

I just ate some really spicy ramen and clearly my mouth and lips were burning. Now, if I were to have touched my eyes or genitals with the sauce on my hands, then that would have burned like hell too. 

However, if the sauce got on my hands, arms, legs, or anywhere else really, there is no sensation of burning. 

I am assuming this has to do with increased nerve endings in the former places, but I'm not sure.
gpt
If you dice hot peppers with your bare hands and don't wash them immediately, you will eventually feel a tingling burning sensation that might take a few days to go away. The difference is the thickness and type of skin tissue being exposed to the capsaicin (spicy chemical). 

Your eyes and mouth are mucus membranes which quickly absorb some of the capsaicin which burns. The rest of your skin has a layer of dead skin cells on top of it, and is not mucus membrane so it absorbs the capsaicin much more slowly, giving you time to wash it off or requiring much more exposure to produce a reaction.