At least two or three times over the last few weeks, I have unlocked my bike and then absent-mindedly locked the cable back onto the front wheel rather than putting it somewhere sensible ...

The state machine in my brain needs some more states.

Sorry to hear your arm hurts. It does sound quite impressive...

What would you say that the difference between being a duhbrain, being incompetent and being clumsy were? The frequency that one does it? The inability to learn from mistakes? The inability to assess the consequences of your actions in advance? The inability to have an accurate enough sense of your own whereabouts?

Difficult question. Hmm.

I think incompetence is a very general term: you can be incompetent at practically anything, including both mental and physical skills. Clumsiness is a specific subclass of incompetence, namely being incompetent at the everyday physical skills that most people don't need to practice (such as opening and closing doors, holding a stationary item in your hand without dropping it, walking on a flat surface without tripping over).

"Duhbrain" I'm reserving here for particularly impressive forms of incompetence, in this case managing a failure mode that I would previously have assumed wasn't even possible. I might also apply it in other different sorts of extreme cases too; it's a word I'll only resort to when I don't think any of the ones I normally use carry enough weight. (Hence, it's only extreme because I'm saying it and it's so far out of character for my normal vocabulary. From a 12-year-old schoolboy it's probably a very mild insult and he'd have to think of something better if he wanted more emphasis.)

Why are we discussing the linguistics of insults in depth, incidentally? I mean, not that it isn't kinda fun, but it's not something I'd have expected to be asked out of the blue :-)

Ah, I was just trying to work out your mapping between clumsiness and stupidity (and working out if it's safe to ever visit you in case you think I'm stupid ;-D