I’ve had a lot of fun with Ruby’s support for functional paradigms but that stuff is unlikely to get through code review when the status quo tends towards ‘Clean Code’ style OOP over-abstraction.

Ruby being a type 2 lisp is a fun one - creating a class and and a factory function with the same name, with argument forwarding:

    class Animal; …; end
    def Animal(…); Animal.new(…); end