What's the deal with the left thumbnail?

This picture was posted on the busblog yesterday. If you don't read the busblog, well, you should. It'll make you laugh, cry, get steaming mad, kiss old people, rub Crisco on your elbows, eat your keyboard and maybe care about other issues than yourself. And then you'll come back for more. But give it time, like many fine things in life, it can be an acquired taste.

Anyway, what's the first thing I noticed about the picture? Answer: the stuff under the left thumbnail. That maybe a weird thing to notice but dammit! this is a mystery I've been trying to figure out for years. This is not to call into question Tony's personal hygiene practices because as I look down at my left thumbnail, I see crap under it too! And there's nothing under any of my other nails.

See, I noticed this trend a long time ago and I have yet to figure out why I get crap under my left thumbnail and only my left thumbnail. I can clean it out and later in the day I look down and ack! it's back. What am I unconsciously doing that I get an unknown substance under my left thumbnail and not under any of the nine other nails?

First of all, what is this mystery substance? Is it just plain dirt? Quite possibly. Is it dingleberries from my asscrack? I'm pretty sure that I don't unconsciously scratch or dig in my pooper with my left thumb during the day so that one's out (but maybe with my right thumb). Is it mashed up ants? Ew. What about pocket lint? Good guess, I'd say. Then there's always really old banana. Nah. Thumbnail juice? Now I'm just making stuff up.

Ok, I'm not really sure what it is but how does it get there? What is my left thumb doing unbeknownst to me? Does it wander off when I'm not looking and go play outside? I know I get dirty sometimes when I play outside. Is it digging a tunnel to China? Every kid knows that this can be done if you dig a hole deep enough and I've always thought of my left thumb as a kid at heart. In its tiny little thumb heart. Maybe it runs off to start revolutionary wars in south american countries. I've always suspected that my thumb had Marxist leanings. I mean, it is my left thumb. I'm pretty sure it hung with Che before we met and it became my thumb. Old habits die hard, I guess.

I don't really know what the answers are but I vow to keep a closer eye on my thumb from now on. You know, for the niños sake.