It's the "spot" your in. Above the "spot" you can get a line. Below this "spot." you are on reserve.

Please don't confuse the G line with the actual G spot. Although they both provide some gratuitous feelings of joy and excitement, it has been observed that one should be above the G line to have an optimum bidding experience. However, if you are below the G line be careful because you may lose your place in the line and feel as though you'll never really find the elusive G spot. If you can't figure it out, you can probably get Colonel Angus to bid for you.