For asexuals, sex is like… a donut. When we see a donut, we do not have the urge to eat the donut. This does not necessarily mean we hate the donut, or think the donut is disgusting— many of us even like donuts. But we never have any urge to walk over there and eat it. Demisexuals will have the urge to eat the donut only if it their absolute favorite kind of donut in the whole world, and greysexuals sometimes will have the urge to get the donut, and sometimes not. Celibates are on diets.