A relatively tame one: make a huge number of tiny donations to effective charities. Donations small enough that they cost more to process than they're worth:

The most extreme case I've seen, from my days working at a nonprofit, was an elderly man who sent $3 checks to 75 charities. Since it costs more than that to process a donation, this poor guy was spending $225 to take money from his favorite organizations. -- GivingGladly