This picture is not crooked. The house is standing up straight. The street is steep. That's why the cars look funny. This is the northern part of Fillmore Street, descending into Cow Hollow on the way to the Marina District.
In a city built mostly on hills, parking gets interesting. In general, turn you wheels toward the curb when you parallel park. That means, turn them as if making a left turn if your car is pointed uphill; turn them as if making a right turn when your car is pointed downhill.
If you don't, the parking authority will write you a ticket. Putting the transmission in park and setting the emergency brake won't always keep a car from rolling down hill. If your wheels are turned to the curb, apparently the car will stop before it can get rolling. I've never tried it.
But on really steep streets like Fillmore, parallel parking with wheels turned to the curb won't do the job, so we park perpendicular to the curb. On the signs it actually says, "90-degree parking only."
This way you can be sure the car won't roll down the hill on its wheels, but if you open the passenger-side door suddenly, it feels as if the car is going to roll over on top of you.