So my home directory is on my secondary volume, so it's actually at /Volumes/Secondary HD/Users/me -- unfortunately the RVM install script when you run "bash < <(curl -s https://rvm.beginrescueend.com/install/rvm)" will output this annoying error "usage: dirname path". It's maddening. I checked the chat logs and Google didn't come up with a fix.
Luckily I busted out my bash-fu to debug the RVM install script. Pro tip -- run bash -x scriptname.sh and it will give you the line number things fail on. I saw that it was failing on line 318. A little digging and I noticed that what was happening was since my directory name has a space, it was borking one of the commands.
So you came here for a fix right? Here's the simple fix.
EDIT: Oops, it looks like RVM doesn't support home directories with spaces in them at all.
According to RVM docs though, you can install as root (run sudo bash to get a root shell) and it will install to /usr/local -- so even though that's not the recommended way to do it for dev users, this seems to be the best way to get it to work if you have a space in your home directory. (As of 2013 this is how you do a "multi user" install, which works just fine.)