Christmas GPS
Christmas GPS
Cueball: Check it out - I got a GPS receiver for Christmas! What should we do with it?
Megan: Let's take our latitude & longitude, put our birthdays after the decimal points, then go to that spot and make out.
[Cueball is in love.]
Merry Christmas from XKCD [ sic ] [Car driving off in to the distance.]

In the comic, Cueball has gotten a GPS device and asks Megan what to do with it. She suggest that they take their current coordinates and modify the latitude and longitude with a simple function based on their birthdays, thereby pointing to an arbitrary, non-random location. For example, if Cueball was born on, let's say, April 1, 1986 and Megan on August 12, 1988 and they are somewhere in New York ( 40.768062,-73.98468 ), the coordinate they type could make ( 40.040186, -73.081288 ) (assuming US date format), or ( 40.860401, -73.880812 ) (assuming following ISO 8601 ). The good thing about keeping the number before the decimal point is that the distance is still realistic to get to by car. Megan suggests to make out in this place. This procedure is somewhat of a precursor to Geohashing .
The comic is a Christmas comic, since it came online on Christmas Day 2006.
The title text suggests that if the location you make for yourselves is over water (which the example above happens to be), you either need to find a boat or find some rule that you can change to preserve the promise of making out, and if you can't do either, then there is no way you'd get to make out.
Cueball: Check it out - I got a GPS receiver for Christmas! What should we do with it?
Megan: Let's take our latitude & longitude, put our birthdays after the decimal points, then go to that spot and make out.
[Cueball is in love.]
Merry Christmas from XKCD [ sic ] [Car driving off in to the distance.]
