Frivolous or bantering talk; a frivolous manner of treating any subject, whether serious or otherwise; light raillery. From the Latin sibilare, ‘to hiss (at), to whistle’.
Sometimes I get curious about who reads this blog. Judging by the number of *.unimelb.edu.au and *.uq.edu.au visitors, I suspect that you’re mostly law students looking for notes. Am I wrong?