I dont find clowns funny and most comedians dont make me laugh, but someone making a complete idiot of themselves without meaning too gets my vote.
I have to add I have a very good sense of humour.
traditionally circus clowns often did the same acts as the serious performers but made a mess of them, so they were a bit like court jesters (or Tommy Cooper, say) mocking the institution they were working for. I don't know that they operate this way any more, though.