Messages sent to the Smalltalk UndefinedObject instance are not silently ignored — #doesNotUnderstand.
Sometimes that run time message lookup has been used to extend behavior —
1986 "Encapsulators: A New Software Paradigm in Smalltalk-80"
https://dl.acm.org/doi/pdf/10.1145/28697.28731
nil class UndefinedObject
nil iainmerrick Object>>doesNotUnderstand: UndefinedObject>>{unbound}doIt
Messages sent to the Smalltalk UndefinedObject instance are not silently ignored — #doesNotUnderstand.
Sometimes that run time message lookup has been used to extend behavior —
1986 "Encapsulators: A New Software Paradigm in Smalltalk-80"
https://dl.acm.org/doi/pdf/10.1145/28697.28731