When having sex, move left to right, as opposed to up and down or forward and back, this is most easlily done by laying on a sleeping bag, or any other slidy surface.
a code used among teens to define a girl's butt in reference to the 3 dimensions on a graph. Z axis is how much it sticks out. Y axis is how tall it is. X axis is how wide it is.
In 3-dimensional Cartesian terms, the x-axis is east and west, the y-axis is north and south, and the z-axis is up and down. So the positive z-axis is what's up.
