[Diesel_Dave]

You're newly married and your wife's car needs the brakes changed. Your wife asks you how long it will take you to do it. You say you're not sure, but not too long.

As you're changing the brakes, you think to yourself, "That's odd, I've worked on my own cars for years. why don't I know off the top of my head how long it takes to change brake pads?"

Then you realize why: you've never had to change the brake pads on any car you've ever owned!