A rating scale for sexual encounters, ranging from negative-infinity to 10, with 10 being the best sex of your life, 0 being the equilibrium where you'd feel the same if you just went home and masturbated, and anything negative is so shameful that masturbating would have been an improvement.
Friend: Yo K, did you hook up with that aweful pancakes girl last night?
K: Yeah, then again this morning, unfortunately.
Friend: Why unfortunately?
K: Ugh, I knew she wasn't going to be really positive on the K-scale, but when I saw her in the daylight she was like a -3.
Friend: Dang dude, you should have just waxed the dolphin yourself.