Myers reminds us the Church sold indulgences for a while until Martin Luther bitched about it.

Bowen recalls hearing about a certain date in the Church calendar when one could gain an indulgence at every church visited on a certain day, and that the faithful were encouraged to visit as many churches as possible, thus 'collecting' indulgences. "The latter are, of course, non-material, and as such would not require bags and it's my assumption is that John is just spoofing the idea of collecting indulgences. In fairness to the Church, I should point out that people were not encouraged to seek indulgences for themselves, but for loved ones who were already deceased and were presumably suffering for their sins in Purgatory. So the earning of indulgences was not exactly a self-centered activity, and the Church certainly advised its members to try to earn their heavenly reward through virtue rather than the accumulation of indulgences. However, there was no rule saying that you couldn't bank them to your own account, if you wanted to."

(also see Catholic Grade School Collections)