USB drive won't show up on boot I plugged the USB thumb drive in, booted my MacBook Pro (8,1) up and held the option key. My USB drive won't show up (I want to install Ubuntu). How to fix this?
As far as I know you can't install linux via bootcamp, its reserved for Windows, however you can create a bootable drive using the guides from help.ubuntu.com

https://help.ubuntu.com/community/MacBookPro8-2/Raring
https://help.ubuntu.com/community/MacBookPro8-2/Quantal