My wife and I put a penny in a bank every time we have sex. I know the exact number of times I've had sex in my life because I've only ever had sex with my wife. I have a wheat penny tattoo on my right leg that I got on our anniversary (I think 6th year). We also know how many times it took to conceive our two kids because we used nickles for one and dimes for the other. We count pennies every anniversary and write down totals and average for the year.