1 - When you're through talking to a friend, before you turn to leave you raise one hand high in the air and say "Thank you very much (ma'am or sir)"

2 - You can't find your car keys then find yourself scratching your head and muttering, "You know, that's gonna bother me."

3 - You don't wash your car for a year and let the door hinges squeak from lack of lube. You know, to give it character.

4 - Your wife asks you to pick up some groceries on the way home and you say "Let me guess. A quart of milk and a head of lettuce"

5 - You go out of your way to find a parking garage so you can whistle 'this old man' and have it echo off the concrete, like in College.

Bonus - Your 4-year-old daughter doesn't say "Daddy! That's this old man." Instead she says, "Daddy! That's Columbo!"

...or.....

1. You and the wife go to the grocery store, she asks you for the list. You fumble around in every pocket telling her "I know I have it here somewhere."

2. You take up cigar smoking even though you've never smoked a day in your life prior to Columbo.

3. You have an elaborate conversation with a friend for five minutes, you leave, then come back saying to him, 'JUST ONE MORE THING.....'

4. You tell peopple that your wife's car is nothing special, just for transporation.

5. You have trouble driving (I.E. almost side-swiping another car, running into garage walls, braking quickly to have the person behind you blow the horn as he passes you, etc...etc....)

And number one on the list:

1) Your life revolves around this forum.