8. Picking Dirt Out Of Your Nails... Using Your Nails...
Even those with immaculate grooming habits probably do this. You examine your hand, find a thin black layer of dirt under your fingernails and then forcibly attempt to extricate it... Using your other, cleaner, fingernails. What this means, in real terms, is that you trade one messy fingernail for two, as you can almost never get it all out in one go. You then attempt to get the crap out of the other finger, using, you guessed it, yet another clean finger... Come on, thats living-in-trees-monkey-minded behaviour people. Youre supposed to be smarter than that.