The purpose of 'figging' is to discourage the recipient of a caning from clenching their bottom cheeks. Since the root burns more when clenching occurs, the victim typically relaxes their muscles and subsequently presents a less tense pair of buttocks to their disciplinarian.
Without going into great anecdotal detail, I can verify that the use of ginger will achieve this result. And wet, fresh, juicy ginger works more insistently than dried out ginger.
This shows what to shape your root into.
And this, of course, shows where it goes.