DrBob

There are almost always two answers:

• a) custom buttplug
• b) exothermic reaction
• source: I worked in an emergency room during training.

Ursula K LeGuin?

I have given up on "steep learning curve". A learning curve is proficiency on the Y axis against time on the X. A steep learning curve indicates something that is learned very quickly. A shallow learning curve is something that takes a long time to master. See Ebbinghaus 1885.