Similar to the "gentleman," which uses a glove rather than a condom.
Gets its name from the esteemed actor Anthony "Tony" Danza, who's career was started in the adult entertainment industry. The danzleman was considered his signature move at the height of his adult entertainment career. The most famous example of the danzleman appeared in the made for late night TV film "Fast Lane Blues" (1977).
(NOTE: The act of slapping someone with the used condom is known as the danzleman, not the fellow wielding the prophylactic, and not Anthony "Tony" Danza.)