Cocksure

We sometimes get 'foreigners' leaving blog post comments here, that they don't understand our peculiar use of the English language - or even getting thrown (confused) buy* just single words that have ambiguous meaning. Google Translate probably has a lot to answer for (is to blame for international miscommunication). Now I have a foreign wife and I'm teaching my young kids to read and write, I'm even more aware of the bizarre irregularities in the English language. The use/meaning of words changes with time and cultural/social climate too. When I was at school the word 'spunk' meant bravado - I can remember our Latin teacher using it. Today it means something else and Latin is no longer taught in schools (is there a connection there?).
Today's word in question is 'cocksure'. I'm not sure of its origin - male fighting chickens? My Collins Gem English Dictionary (printed in 2004) lists it as: '(adjective) overconfident, arrogant'. To me there has to me some male swagger in there - I wouldn't say overconfident, but definitely large balls (testicles) clanging - like Marco Melandri here.... BP *UPDATE:
Beste Adriaan,
I really didn't get your 'buy, bye, or by?' comment, and was too busy to scratch my head over it for any length of time. Now my editor has pointed out more specifically that it was a typo. Like my Dutch wife, you are evidently better at spelling English than me. BP