a
callus caused by a
2nd degree burn, usually caused by touching an
extremely hot surface. For example, touching the
engine block of a motorcycle while using a
mini kryptonite and a
kryptonite cable lock to secure said motorcycle against all but the most determined liberators.
I looked at it, thought that's gonna hurt, and proceeded to spend the next four hours pointing at icecubes. (With minor painful interruptions to do a bit of mig welding for myself and others)
Happy coincidence is that the callus is most useful for mousing with a trackpad.