Simple, yet used rarely enough to be forgettable.
$ rails c
 pry(main)> require 'factory_girl'
 pry(main)> FactoryGirl.find_definitions
 pry(main)> FactoryGirl.create :my_thing
Wow! The rails + rspec error codes are a mess. This tip is really useful!!!
To avoid appending FactoryGirl at the beginning of every create, also run:
 pry(main)> include FactoryGirl::Syntax::Methods