In Ruby, objects have a handy method called method_missing which allows one to handle method calls for methods that have not even been (explicitly) defined:
I was looking for this before, and found a useful list (quickly being overtaken here) as part of the Merd project on SourceForge.
Construct Language
----------- ----------
AUTOLOAD Perl
AUTOSCALAR, AUTOMETH, AUTOLOAD... Perl6
__getattr__ Python
method_missing Ruby
doesNotUnderstand Smalltalk
__noSuchMethod__(17) CoffeeScript, JavaScript
unknown Tcl
no-applicable-method Common Lisp
doesNotRecognizeSelector Objective-C
TryInvokeMember(18) C#
match [name, args] { ... } E
the predicate fail Prolog
forward Io
With footnotes: