If you refuse to read the documentation on https://rvm.io/, you can usually just get up and running by blindly entering these commands into your terminal:
$ gpg --keyserver hkp://keys.gnupg.net --recv-keys 409B6B1796C275462A1703113804BB82D39DC0E3
$ curl -sSL https://get.rvm.io | bash -s stable
$ source ~/.rvm/scripts/rvm
$ rvm install ruby-head
$ rvm use ruby-head --create
$ gem install bundler
ok fine....
This also not worked for me...