... you carry your bike commuter map with you everywhere, and use it to give car drivers directions.

... there are some things you only know how to get to by bike.
Oh, I have *so* done these!

...you assess the shoulder width, hilliness, and road conditions from a bicyclist's perspective even when in a car.
I was gonna come back and post that one, but ya beat me to it!

...you have to drive to work one day for some reason, and find you have nothing much to wear - all your favorite clothes are in your locker at work

...you do much of your clothes / household items shopping at thrift stores and hate to pay more than five or six dollars for a blouse or a set of dishes...but think nothing of saving up over a hundred to pay for panniers or lights, or spending seventy or eighty on a saddle.