Albrecht of Mainz (June 28, 1490 – September 24, 1545) was an ambitious churchman who had one diocese but wanted to acquire another. For this, he needed papal permission. Pope Leo X was willing to offer him another diocese should Albrecht make a donation to the building project of Saint Peter's Basilica in Rome.
To acquire such a cash infusion, Albrecht of Mainz went on an "indulgence drive." He effectively sold indulgences—remissions of sins purchased to reduce one's time spent in purgatory—to gather enough money to bribe the Pope to let him oversee (and collect the revenues from) a second diocese.
To speed along his plan, Albrecht hired Johann Tezel as a shill to preach the importance of buying indulgences. Tezel came up with a memorable little jingle: "as soon as the coin in the coffers rings, the soul out of purgatory springs."
This kind of corruption incensed Martin Luther and other reformers and perhaps created an atmosphere amenable to the spread of Protestantism.