I thought the bike shop was joking when they told my sister they could get the assometer out to properly measure her for a saddle. I decided to google this just for fun and to my surprise there is actually such a thing out there. Specialized bikes have come up with this concept to measure your ischial tuberosities (otherwise known as your sit bones). Apparently no matter how much or how little padding you have it does not correlate to the width of your sit bones as most people would believe. Therefore you could have a really big assometer reading and actually have a very little behind and vice versa. Due to this anomaly Specialized developed this pad that you sit on and then they measure the indentations made by your sit bones to determine which width of saddle you need.
This makes me curious to find out who has the bigger assometer reading. Me or my sister. Who would have ever thought of such a thing? Specialized bikes, I guess.