Explaining belief in the absurd

[The Stranger]

How about telling your kids about santa claus? its both impossible and lying which is socially inappropriate. :P

does the absurd has to be both impossible and culturally/socially inappropriate or can it be either impossible or culturally/socially inappropriate or both? If it is the former I dont really see why it has to, for me belief in the clearly impossible (according to ones own views) is already rather absurd.

yet at the same time, often people regard something as absurd even if its not impossible but only culturally/socially inappropriate. (such as the belief hitler was a good man for example)