1) You tuck in your shirt. This comes from a gradual recognition that you probably won't end up in a pickup game of baseball or tag. It's more likely that you'll run into some professional acquaintance or have to go to the bank.
2) You listen to Talk Radio. You used to listen to Rush and now you listen to Rush Limbaugh. It's a sad trade.
3) You start sentences with "Remember when..." Nothing says "old" like reminiscing about the good old days when the internet was still in black and white and you could buy a car for a nickel.
4) You file taxes. Part of being an adult is being a slave to the man. You must make real money and then have it taken away from you.
5) You know what APR means. There are several codes that you must understand in order to be a real adult. APR is one of them. No, it does not mean "Average Parental Rating." I have a feeling it has to do with mortgage (whatever that means).
6) You read the newspaper, and not just the funnies. Part of being an adult is finding fulfillment in the unfulfilling filler.
7) You part your hair or have parted with your hair. 'Nuff said.
8) You care about politics. As if there is more to life than light-up shoes and candy. Hmf, as if....
9) You give directions using North, South, East, and West. This skill comes with an awareness of a world that exists beyond your street. Still, tucked away in the corner of your heart you know that NESW really is a reminder to Never Eat Slimy Worms.
10) You eat bran cereal. Might as well go chomp on some woodchips. Can't sugar binge anymore? Yeah, you're probably an adult.
11) You like sleeping but you never get to. This is probably the biggest irony of being an adult.
Your turn. Tell us how you know you're an adult.