When a chick is smokin hot, but there is something about her that gets in the way of giving her a perfect 10. Usually she is hot but way too dumb, or just used a double (or triple) negative and has low self esteem. If your dick is doing the thinking she is a 9.9, but if your brain kicks in even a little bit she drops to a 9.1 or so. Hence the confusion and she hangs out in the 9. something area depending on your mood.

to tell someone to calm down and relax.