The fact that 99.83 percent of the times that you get your front-door key copied at the hardware store for your very important houseguest (say, a mother-in-law visiting the first time in 10 years), the shiny new duplicate will not work. The only way around this is to get six keys made as insurance. Consider this an investment in your sanity instead of a tax on your patience.

You had the argument with the claim representative and, as it turns out, insurance won't cover your wig because you lost your hair to cancer, not an explosion in your house. Forcing you to realize, yet again, that your soul cannot be broken by rude trained-to-be-heartless employee and for-profit-only logic, and that somebody you love somewhere will still get very, very drunk with you if you hang up the phone and re-approach this tomorrow.

On the two days a year that you get to take a nap in the middle of the day, the neighbor's kids will get a new Roman-candle set from their Uncle Duncan.

Pimples after age 40.

Age spots before age 40.

Possibly even more unfair: You get a $500 gift certificate to a glamorous French skin-cream store from your husband—due to all the pimples and age spots. You have never, ever gotten a $500 gift certificate to anything and save it for one year, trying to use up all your crappy drugstore creams, before going to have this amazing face-changing experience, because you may be 41 but you are not wasteful. You book a date for a skin assessment. You go in. The store has closed; the entire chain has gone bankrupt. How to cope? Know that you are not alone. This has happened to me (numbers 4 through 6).

She likes all your friends. You like her. But she doesn't like you. Which can be dealt with by remembering that she can't say or do much about it for fear of your friends not liking her.