Long before the blessed holy clothes and apocalyptic tapes, it appears that religious organizations found a way to fleece the faithful. Smith College has reconstructed a coin-operated holy water dispenser designed by the Greek inventor Heron.
The dispenser was used at Egyptian temples and the faithful could drop in a coin to get a squirt of holy water. Just drop a drachma and be saved. Of course, this was when televangelists were just templevangelists. However, it was still non-taxable income and there was a steady stream of holy water to dispense.
For the mechanics and pictures, click here.
If, as the linked explanation states, merely the weight of the coin starts the water flowing, then people sometimes must have used slugs.