Gary Bernhardt gave a 4-min lightning talk at CodeMash 2012 about the perks and weird behaviours on Ruby and Javascript.
[You can find the presentation on destroyallsoftware.com][1]
or [downloading it here][2].
It is a humour approach on these perks and helps you remembering them in daily work. With its five minutes it easy and quick to consume but will keep you from wasting hours of banging your head against the wall. I also highly recommend reading this [stack overflow explaining where all these behvaiurs come from and how to use them for good instead of evil][3].
[1]: https://www.destroyallsoftware.com/talks/wat
[2]: https://s3.amazonaws.com/destroyallsoftware-talks/wat.mov?AWSAccessKeyId=AKIAIKRVCECXBC4ZGHIQ&Expires=1399217130&Signature=XMfoXvDtLRa9Uflfbsigi78HDqY=
[3]: http://stackoverflow.com/questions/9032856/what-is-the-explanation-for-these-bizarre-javascript-behaviours-mentioned-in-the/9033306#9033306