How do I pick randomly from an array?
Just use Array#sample:
[:foo, :bar].sample # => :foo, or :bar :-)
It is available in Ruby 1.9.1+. To be also able to use it with an earlier version of Ruby, you could require "backports/1.9.1/array/sample".
Note that in Ruby 1.8.7 it exists under the unfortunate name choice; it was renamed in later version so you shouldn't use that.
Although not useful in this case, sample accepts a number argument in case you want a number of distinct samples.
myArray.sample(x) can also help you to get x random elements from the array.