subitus - sudden in the sense of spontaneous, unplanned (perhaps), off the cuff

Audivi causas agentem acriter et ardenter nec minus polite et ornate, sive meditata sive subita proferret Pliny, Ep. 1 16 Ainsworth has hasty, unlooked for, sudden

Comments

utram tandem linguam nescio - Cicero, de Fin. II 12