VIDEO : Demi Lovato, Nick Jonas Join James Corden on 'Carpool Karaoke'

Lovato and Jonas, who have been friends for 10 years and are about to go out on tour together, brought very special chemistry to Carpool Karaoke with plenty embarrassing stories ? mostly at Jonas' expense. Lovato detailed the cyclical pattern of singer's dating life, while both she and James Corden tittered about the days of the Jonas Brothers and their infamous purity rings.