+@.rb

# so, we had a bug from a line of code doing this:

something_that_may_be_symbol_or_str.to_s +"something"
# => undefined method `+@' for "something":String

# TIL:
Derp = Class.new { def +@; puts 'WAT'; end }
# => Derp 
+Derp.new
# => WAT

# but what is really weird is:

derp = 'hi'
# => "hi" 
derp +'hi'
# => "hihi"
derp.to_s +'hi'
# => NoMethodError: undefined method `+@' for "hi":String

neat.rb

# haha, YES!

class MyNumber; @@number = 0; def +@; @@number += 1; end; end

number = MyNumber.new
# => #<MyNumber:0x000001008fb460> 

++number
# => 1 
++number
# => 2 
++number
# => 3