G is the seventh letter in the English American language alphabet, and is one of the dirtier letters since it is used to start the word "Gay." It's also adjacent in the alphabet to the letter "F" and we all know what that stands for. For the moment we will completely ignore is successor, "H", and the hideousness of it.
G also marks a particular spot, and if you know where it is, your female partners will be very happy with your exploitations of their sexness.
"Air on a G String" is not what it sounds like. It's a geeky chapter in a book for geeks.
- To elaborate, G is the musical note a fifth above C. Many string instruments have a string tuned to G. Never make joking references to this and the garment also known as a G string in front of people who play such instruments. They have heard it before, they are sick of it, and they may decide to strangle you. Probably with a G string.