I'd never heard the term before, but it's straight out of Yes Minister (Humphrey showing how choice of questions can lead to the same person giving polar opposite answers on whether conscription should be reintroduced).
I thought phone campaigning was not allowed - as Labour MP David Lammy found out when he was fined by the courts for making nuisance calls
I am aghast that this campaign had resorted to such a level of dirty tricks. It has certainly influenced my vote.