Is it common knowledge
that humour
is derived from the unexpected?

It is.

As a result,
any thing found funny
is an expectation
that has been turned
on its head.

Why do senses of humour differ?

They don’t.

How then,
does one person
find something funny,
while another
does not?

Buy-in.

In order to have
an expectation,
one must be bought-in
to the narrative.

Therefore,