The what: "The wild Colonial Boy", which hashes to 4c46256d89e3d5ce17d8ea5aff2b31852bc6d09d293e9c324658d914ead92fc9, which is the Brain Wallet passphrase.
The how: This is what I did to get the answer:
1. A "strain" would understand "strine". I didn't know what this meant, so I googled "strine". It's Aussie slang for Australian.
2. The remaining clue is "wild". So next, I google "wild Australian".
3. Nothing useful comes up, so I look at the remaining clues. "from a song"... so next I googled "wild Australian song".
4. First result was "The Wild Colonial Boy". Tried it, but didn't work. Looked back in the thread... "second word starts with a lower case letter"... Tried "The wild Colonial Boy", and it worked!
This is slightly abbreviated. There were a few detours I took during the sequence of events (the Australian national anthem, "Come along my hearties", etc.).
BTW I am guessing if the reward was a lot higher then someone might have actually created a bot just to crack it.
Even so by doing something unusual (here I just hashed so probably something a little more exotic would be preferable) - and of course not publishing that information - brainwallets can be made much more secure.
Indeed. Remember that humans can't remember sequences of arbitrary data well (try memorizing "z,@M!.xaQE"), but can remember procedures. So making up your own procedure can turn a weak brainwallet into a strong one. More exotic procedures include various hashes, concatenation, reversing the phrase, repeating certain words, padding with spaces or punctuation, adding Chinese characters, or anything else you can think of.